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M1 2 ⁢ ∑ a ⁢ b

M2 x ′ 3

M3 f ′ ⁡ ( x ) + sin ⁡ cos ⁡ θ = 1

M4
f ⁡ ( z ) = ∑ n = 0 ∞ a n ⁢ z n ,  | z | < R ⁣ ( R ≠ 0 )

M5
∫ C ( ∑ n = 0 ∞ a n ⁢ z n ) ⁢ ⅆ z = ∑ n = 0 ∞ a n ⁢ ∫ C z n ⁢ ⅆ z

M6
lim n → ∞ | ∫ C [ f ⁡ ( z ) − ∑ k = 0 n a k ⁢ z k ] ⁢ ⅆ z | = 0

M7
n ≥ N ⁡ ( ε ) ⇒ | f ⁡ ( z ) − ∑ k = 0 n a k ⁢ z k | < ε

M8 10  Bq + 10  Ci

M9 10  amol + 10  Emol − 10  fmol + 10  Gmol − 10  kmol + 10  Mmol

M10 10  μmol + 10  mmol − 10  mol + 10  nmol − 10  Pmol + 10  pmol − 10  Tmol

M11 10  acre + 10  hectare − 10  ft 2 + 10  in 2 − 10  m 2

M12 10  A + 10  kA − 10  μA + 10  mA − 10  nA

M13 10  F + 10  μF − 10  mF + 10  nF − 10  pF

M14 10  C + 1.0  m/s/s − 0.1  m / s 2

M15 10  kS + 10  μS − 10  mS + 10  S

M16 10  kV + 10  MV − 10  μV + 10  mV − 10  nV + 10  pV − 10  V

M17 10  GΩ + 10  kΩ − 10  MΩ + 10  mΩ − 10  Ω

M18 10  Btu + 10  cal − 10  eV + 10  erg − 10  GeV + 10  GJ

M19 10  J + 10  kcal − 10  kJ + 10  MeV − 10  MJ + 10  μJ − 10  mJ + 10  nJ

M20 10  dyn + 10  kN − 10  MN + 10  μN − 10  mN + 10  N − 10  ozf + 10  lbf

M21 10  EHz + 10  GHz − 10  Hz + 10  kHz − 10  MHz + 10  PHz − 10  THz

M22 10  fc + 10  lx − 10  phot

M23 10  Å + 10  am − 10  cm + 10  dm − 10  fm + 10  ft − 10  in

M24 10  km + 10  m − 10  μm + 10  mi − 10  mm + 10  nm − 10  pm

M25 10  sb

M26 10  lm

M27 10  cd

M28 10  Mx + 10  μWb − 10  mWb + 10  nWb − 10  Wb

M29 10  G + 10  μT − 10  mT + 10  nT − 10  pT + 10  T

M30 10  H + 10  μH − 10  mH

M31 10  u + 10  cg − 10  dg + 10  g − 10  kg + 10  μg − 10  mg + 10  lb − 10  slug

M32 10  ° + 10  μrad − 10  mrad + 10 ​ ′ − 10  rad + 10 ​ ′′

M33 10  GW + 10  hp − 10  kW + 10  MW − 10  μW + 10  mW − 10  nW + 10  W

M34 10  atm + 10  bar − 10  kbar + 10  kPa − 10  MPa + 10  μPa − 10  mbar + 10  mmHg − 10  Pa + 10  torr

M35 10  sr

M36 10  °C + 10  °F − 10  K

M37 10  as + 10  d − 10  fs + 10  h − 10  μs + 10  ms − 10  min + 10  ns − 10  ps + 10  s − 10  y

M38 10  ft 3 + 10  in 3 − 10  m 3 + 10  gal − 10  l

M39 10  ml + 10  pint − 10  qt

M40 1 x ⁡ ( y ) = ( − ∫ e − 1 2 ⁢ y 2 ⁢ sin ⁡ y ⁢ ⅆ y + C 1 ) ⁢ e 1 2 ⁢ y 2

M41 ⅅ x y − y = sin ⁡ x

M42 ( 1 2 ) ⁢ ( 1 2 ) ⁢ ( 1 2 )

M43
[ 1 2 ] ⁢ ( 1 2 ) ⁢ { 1 2 }

M44 ⟨ 1 2 ⟩ ⁢ ⌊ 1 2 ⌋ ⁢ ⌈ 1 2 ⌉

M45
↑ 1 2 ↑ ⁢ ↓ 1 2 ↓ ⁢ ↕ 1 2 ↕

M46 1 2 ⁢ 1 2 ⁢ 1 2

M47
1 2 ⁢ 1 2 ⁢ 1 2

M48 1 2 ⁢ 1 2 ⁢ 1 2

M49 − ( a − b ) = b − a

M50 2 5 + 3 7 = 2 ⋅ 7 + 3 ⋅ 5 35 = 29 35

M51
| a | = { a if a ≥ 0 − a if a < 0

M52
a n = a ⋅ a ⋅ ⋯ ⋅ a ⏟ n  factors

M53 ( a b ) − n = ( b a ) n

M54
a n = b   means  b n = a .

M55 16 81 4 = 16 4 81 4 = 2 3

M56 { x ∣ x ≠ 0 , x ≠ 1 }

M57
a n ⁢ x n + a n − 1 ⁢ x n − 1 + ⋯ + a 1 ⁢ x + a 0

M58 a 3 − b 3 = ( a − b ) ⁢ ( a 2 + a ⁢ b + b 2 )

M59 ( x + y ) 2

M60 H = { ( a b c d ) ∈ G ∣ a ⁢ d − b ⁢ c = 1 }

M61 | x | + || y || + { z } − [ a ⁢ c ] + ( b ) = [ a , b ]

M62 x = 1

M63 x = 1

M64 x = 1

M65 x = 1

M66
[ − 10 3 , − 7 3 ) ∪ ( − 7 3 , − 4 3 ]

M67
A ⁢ ∂ u ∂ x + B ⁢ ∂ u ∂ y + C ⁢ u = E

M68 ∑ ​ ​ x

M69 ∑ 1 < i < 10 1 < j < 10 ​ 2 i + j

M70 Γ 1 2 3 4 ​ 5 6 7 ​ ​ 1 5 7 6 2 4 3

M71 y ⁡ ( x ) = x ⁢ e x − e x + 2 e x = x − 1 + 2 e x

M72 ⅅ x ⁣ x y − y = 0 y ⁡ ( 0 ) = 1 y ′ ⁡ ( 0 ) = 0

M73 y ⁡ ( x ) = 1 3 ⁢ e − ( − 1 ) 3 ⁢ x + 2 3 ⁢ e 1 2 ⁢ ( − 1 ) 3 ⁢ x ⁢ cos ⁡ 1 2 ⁢ 3 ⁢ ( − 1 ) 3 ⁢ x

M74 y ⁡ ( t ) = 2 ⁢ tan ⁡ ( 2 ⁢ t − 1 4 ⁢ π )

M75 ℱ ⁡ ( e 2 ⁢ π ⁢ i ⁢ x 2 ⁢ π ⁢ Dirac ⁡ ( x − 2 ⁢ π ) , x , s ) = ( 2 ⁢ π ⁢ Dirac ⁡ ( s − 2 ⁢ π ) 2 ⁢ π ⁢ e − 2 ⁢ i ⁢ π ⁢ s )

M76
x = 1 x + 3 = 123

M77 t x y z 0 1.0000 1.0000 1.0000 .1 1.1158 1.0938 .8842 .2 1.2668 1.1695 .7332 .3 1.4582 1.2173 .5418 .4 1.6953 1.2253 .3047 .5 1.9830 1.1791 .0170 .6 2.3256 1.0619 − .3256 .7 2.7265 .8542 − .7265 .8 3.1873 .5344 − 1.1873 .9 3.7077 .0777 − 1.7077 1.0 4.2842 − .5424 − 2.2842

M78 K v ⁡ ( z ) = BesselK v ⁡ ( z )

M79
z 2 ⁢ ⅆ 2 w ⅆ z 2 + z ⁢ ⅆ w ⅆ z − ( z 2 + v 2 ) ⁢ w = 0

M80
∂ 2 u ⁡ ( x , y ) ∂ x 2 − ∂ 2 u ⁡ ( x , y ) ∂ y 2 = 0

M81 y ⁡ ( t , x ) = F 1 ⁢ ( − x − a ⁢ t ) + F 2 ⁢ ( x − a ⁢ t )

M82 1 2 3 4 5 6

M83
2 ⁢ x + 1 = 5

M84
1 = 3 9 = 7

M85
a ⁢ b c ⁢ d e ⁢ f

M86
x + 2 ⁢ y − 3 = 5 4 ⁢ x − y − 5 = 98

M87
x = z 1 = 3

M88
A 1 = N 0 ⁡ ( λ ; Ω ′ ) − φ ⁡ ( λ ; Ω ′ ) , A 2 = φ ⁡ ( λ ; Ω ′ ) − φ ⁡ ( λ ; Ω ) , A 3 = N ⁡ ( λ ; ω ) .

M89
sin ⁡ θ cos ⁡ γ

M90 x = { x if  x < 0 − x if  x ≥ 0

M91 L ⁢ M ⁢ R ⁢ M L ⁢ M ⁢ R ⁢ M

M92 M ⁢ A ⁢ T ⁢ H M ⁢ A ⁢ T ⁢ H

M93

M94 ⋮

M95 ∇× F = 0

M96 ∇· F

M97 ∇·∇ F = ∇ 2 F + 7 = A

M98 ∇× ( x ⁢ y , y ⁢ z , z ⁢ x ) = [ − y − z − x ]

M99 ∇× ( y , z , x ) = ( − 1 , − 1 , − 1 ) ≠ 0

M100 x + y + α = 102

M101 a + b = c

M102 x + 1

M103 x + f ⁡ ( x ) − 1 = 123

M104 T ⁢ h ⁢ e ⁢ q ⁢ u ⁢ i ⁢ c ⁢ k ⁢ b ⁢ r ⁢ o ⁢ w ⁢ n ⁢ f ⁢ o ⁢ x ⁢ j ⁢ u ⁢ m ⁢ p ⁢ s ⁢ o ⁢ v ⁢ e ⁢ r ⁢ t ⁢ h ⁢ e ⁢ l ⁢ a ⁢ z ⁢ y ⁢ d ⁢ o ⁢ g . T ⁢ h ⁢ e ⁢ e ⁢ n ⁢ d .

M105 ( ∂ f ∂ x 1 ⁡ ( c 1 , c 2 , … , c n ) , ∂ f ∂ x 2 ⁡ ( c 1 , c 2 , … , c n ) , … , ∂ f ∂ x n ⁣ 1 ⁡ ( c 1 , c 2 , … , c n ) )

M106 ∇ ( c ⁢ u ⁢ v + v 2 ⁢ w ) = ( u ⁢ v , c ⁢ v , c ⁢ u + 2 ⁢ v ⁢ w , v 2 )

M107
D u ⁢ f ⁡ ( a , b , c ) = ∇ f ⁡ ( a , b , c ) ⋅ u = ∂ f ∂ x ⁡ ( a , b , c ) ⁢ u 1 + ∂ f ∂ y ⁡ ( a , b , c ) ⁢ u 2 + ∂ f ∂ z ⁡ ( a , b , c ) ⁢ u 3

M108 θ ∈ { π + 2 ⁢ X 3 ⁢ π − ( arccos ⁡ 1 7 ⁢ 14 ) | X 3 ∈ ℤ } , θ ∈ { 2 ⁢ X 4 ⁢ π − π + ( arccos ⁡ 1 7 ⁢ 14 ) | X 4 ∈ ℤ }

M109 P = A ⁢ ( A T ⁢ A ) − 1 ⁢ A T

M110 det ( x y 1 a b 1 a d 1 ) = x ⁢ b − x ⁢ d + a ⁢ d − a ⁢ b = 0

M111
A ⁡ ( θ ) ⁢ A ⁡ ( − θ ) = [ cos ⁡ θ − sin ⁡ θ sin ⁡ θ cos ⁡ θ ] ⁢ [ cos ⁡ θ sin ⁡ θ − sin ⁡ θ cos ⁡ θ ]

M112 J ⁡ ( A ) = [ J n 1 ⁡ ( λ 1 ) 0 ⋯ 0 0 J n 2 ⁡ ( λ 2 ) ⋯ 0 ⋮ ⋮ ⋱ ⋮ 0 0 ⋯ J n k ⁡ ( λ k ) ]

M113 det ( − 4 + X − 1 0 0 − 4 + X 0 0 0 − 4 + X ) = ( X − 4 ) 3

M114 { ( − 1 2 − 1 6 ⁢ 33 1 ) } ↔ 5 2 − 1 2 ⁢ 33

M115
∥ A ∥ = max x ≠ 0 ∥ A ⁢ x ∥ ∥ x ∥

M116 ( a 1 ⁣ 1 a 1 ⁣ 2 a 2 ⁣ 1 a 2 ⁣ 2 ) + ( b 1 ⁣ 1 b 1 ⁣ 2 b 2 ⁣ 1 b 2 ⁣ 2 ) = ( a 1 ⁣ 1 + b 1 ⁣ 1 a 1 ⁣ 2 + b 1 ⁣ 2 a 2 ⁣ 1 + b 2 ⁣ 1 a 2 ⁣ 2 + b 2 ⁣ 2 )

M117 f ⁡ ( [ 1 2 4 3 ] ) = [ 1 2 4 3 ] 2 − 5 ⁢ [ 1 2 4 3 ] − 2 = [ 2 − 2 − 4 0 ]

M118 x = lim x = 1 ∑ 1 2 a

M119
∫ a b f ⁡ ( x ) ⁢ ⅆ x = lim ∥ P ∥ → 0 ∑ i = 1 n f ⁡ ( x ‾ i ) ⁢ Δ x i

M120 ∫ a b f ⁡ ( x ) ⁢ ⅆ x = lim n → ∞ b − a n ⁢ ∑ i = 1 n f ⁡ ( a + i ⁢ b − a n )

M121 ∫ 0 2 x 5 ⁢ x 3 + 1 ⁢ ⅆ x = ∫ 1 3 2 3 ⁢ u ⁢ ( u 2 ) ( u 2 − 1 ) 2 3 ⁢ ( u 2 ⁢ ( u 2 − 1 ) 2 3 − ( u 2 − 1 ) 2 3 ) ⁢ ⅆ u

M122
∫ f ⁡ ( g ⁡ ( x ) ) ⁢ g ′ ⁡ ( x ) ⁢ ⅆ x = ∫ f ⁡ ( u ) ⁢ ⅆ u

M123 x = 2 ⁢ ∑ n = 1 100 n ⁢ ( n − 1 )

M124 lim x → 0 sin ⁡ ( 1 x ) = − 1 .. 1

M125 h ⁡ ( i , j ) = ( 2 − j ) ⁢ g ⁡ ( i ) + ( j − 1 ) ⁢ f ⁡ ( g ⁡ ( i ) )

M126 △ : [ 0 , 1 ] → [ 0 , 1 ]

M127 0 ▽ x = x

M128 x △ y = h − 1 ⁢ ( h ⁡ ( x ) ⁢ h ⁡ ( y ) )

M129 x △ y = f − 1 ⁢ ( max { f ⁡ ( x ) + f ⁡ ( y ) − 1 , 0 } )

M130 x ▽ y = η ⁡ ( η ⁡ ( x ) △ η ⁡ ( y ) )

M131 x ⁢ △ 0 y = { x ∧ y if x ∨ y = 1 0 if x ∨ y < 1

M132 lim a → 1 + log a ⁡ [ 1 + ( a x − 1 ) ⁢ ( a y − 1 ) a − 1 ] = lim a → 1 − log a ⁡ [ 1 + ( a x − 1 ) ⁢ ( a y − 1 ) a − 1 ] = x ⁢ y

M133 g ⁡ ( x ) = exp ⁡ ( − 1 − ( 1 − x ) a ( 2 a − 1 ) ⁢ ( 1 − x ) a )

M134
Aut ( I ) = { f : [ 0 , 1 ] → [ 0 , 1 ] | f  is one-to-one and onto, and x ≤ y  implies  f ⁡ ( x ) ≤ f ⁡ ( y ) }

M135
x 2 + y 2 = r 2 ,    tan ⁡ θ = y x

M136 2 ⁢ 1 − t 2

M137 [ ( 2 + sin ⁡ t ) ⁢ 10 ⁢ cos ⁡ t , ( 2 + cos ⁡ t ) ⁢ 10 ⁢ sin ⁡ t , 3 ⁢ sin ⁡ 3 ⁢ t ]

M138 { t = 0 , s = 0 } , { t = π , s = π }

M139
1 2 3 4 5 6 7 8 9 10 2 4 6 8 10 1 3 5 7 9 3 6 9 1 4 7 10 2 5 8 4 8 1 5 9 2 6 10 3 7 5 10 4 9 3 8 2 7 1 6 6 1 7 2 8 3 9 4 10 5 7 3 10 6 2 9 5 1 8 4 8 5 2 10 7 4 1 9 6 3 9 7 5 3 1 10 8 6 4 2 10 9 8 7 6 5 4 3 2 1

M140
testing  x 2  end.

M141 x

M142 x

M143 x

M144 x

M145 ⅆ f ⅆ x ⁡ ( x 1 ) = 5

M146 ∫ x ⁢ ⅆ x = ∬ x ⁢ y ⁢ ⅆ x ⁢ ⅆ y = ∭ x ⁢ y ⁢ z ⁢ ⅆ x ⁢ ⅆ y ⁢ ⅆ z = ⨌ x ⁢ y ⁢ z ⁢ t ⁢ ⅆ x ⁢ ⅆ y ⁢ ⅆ z ⁢ ⅆ t

M147 mod a

M148 5 mod 3 = 2

M149 f ⁡ ( 0 ) mod 3 = 1

M150 5 ⁢ x + 4 ≡ 8 ⁣ ( mod 13 )

M151 a = ( 5 − 3 ) / 5 mod 7 = 6

M152 ( 2 ⁢ x 2 + x + 2 ) + ( 2 ⁢ x + 1 ) mod 3 = 2 ⁢ x 2

M153 + 0 1 000 000 111 1 1 0

M154 4. 974 9

M155 ⅆ ⅆ x F ⁡ ( x )

M156 [ 86.333 , 146.33 , 129.33 ]

M157 BinomialDist ⁡ ( x ; n , p ) = ∑ k = 0 x ( n k ) ⁢ p k ⁢ q n − k

M158 Pr ( X ≤ 54 ) = BinomialDist ⁡ ( 54 ; 100 , .55 ) = .45846

M159
k = max { | ∂ f ∂ y ⁡ ( x , y ) | : ( x , y ) ∈ D } .

M160
m = lim x → a f ⁡ ( x ) − f ⁡ ( a ) x − a

M161
| A | = | a 1 ⁣ 1 a 1 ⁣ 2 ⋅ ⋅ ⋅ a 1 ⁣ n a 2 ⁣ 1 a 2 ⁣ 2 ⋅ ⋅ ⋅ a 2 ⁣ n ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ ⋅ a n ⁣ 1 a n ⁣ 2 ⋅ ⋅ ⋅ a n ⁣ n | = a 1 ⁣ 1 ⁢ A 1 ⁣ 1 + a 1 ⁣ 2 ⁢ A 1 ⁣ 2 + ⋯ + a 1 ⁣ n ⁢ A 1 ⁣ n

M162
x = 1 ( hl text  x  end. )

M163
x = 1 ( hl to URI  x  end )

M164
x = 1 ( sex )

M165
x = 1 ( jbm )

M166

M167 f ⁡ ( x ) ⁢ g ⁢ [ y ] ⁢ h ⁢ { z } + ⌊ a ⌋ ⁢ ⌈ b ⌉ ⁢ ⟨ c ⟩

M168 123 456 A | ∥ A B A / 1 2 A / ⁢ ( 3 4 A ) ↕ 5 6 A ↕ 7 8 A ⇕ 9 20 10 A ⇕ ↑ 11 12 A ↑ ⁢ ⇑ 13 14 A ⇑ ↓ 15 16 A ↓ ⇓ 17 18 A ⇓

M169 x ⁢ x x x x ⁢ x

M170
( a 1 , a 2 , … , a n ) ⋅ ( b 1 , b 2 , … , b n ) = a 1 ⁢ b 1 * + a 2 ⁢ b 2 * + ⋯ + a n ⁢ b n *

M171
⌊ n 5 ⌋ + ⌊ n 5 2 ⌋ + ⌊ n 5 3 ⌋ + ⌊ n 5 4 ⌋ + ⋯

M172 x 1 + ⋯ + x n

M173 x + ⋯ + x ⏟ k  times

M174 x 1 ⁢ x 2 ⁢ ⋯ ⁢ x n n

M175 n ! = 1 × 2 × 3 × 4 × ⋯ × n

M176 P : a = x 0 < x 1 < x 2 < ⋯ < x n = b

M177
f ⁡ ( x ) = 30 13 ⁢ cos ⁡ x + 10 3 ⁢ ( 100 + 9 cos 2 ⁡ x − 60 cos ⁡ x ⁢ sin ⁡ ( x + 29 90 ⁢ π ) )

M178
∫ cos ⁡ ( A ⁢ x ) ⁢ sin ⁡ ( B ⁢ x ) ⁢ ⅆ x = − cos ⁡ ( B − A ) ⁢ x 2 ⁢ ( B − A ) + − cos ⁡ ( B + A ) ⁢ x 2 ⁢ ( B + A ) + C  .

M179 235.3 + 813 = 1048. 3

M180 max − 2 ≤ x ≤ 2 ( x 3 − 6 ⁢ x + 3 ) = 8.0

M181 x ⁢ decade = 2 ⁢ century

M182
ⅆ 5 ( x 7 − 3 ⁢ x 6 ) ⅆ x 5    ⅆ n sin ⁡ x ⅆ x n    ⅆ 3 ⅆ x 3 f ⁡ ( x )    ⅆ 2 ⅆ t 2 ( 4 ⁢ t 5 − 3 ⁢ t )

M183 f ⁡ ( x ) = 30 13 ⁢ cos ⁡ x + 10 3 ⁢ ( 100 + 9 cos 2 ⁡ x − 60 cos ⁡ x ⁢ sin ⁡ ( x + 29 90 ⁢ π ) )

M184
∫ R 3 ( | u 1 | 2 + | ∇ u 0 | 2 2 + | u 0 | 6 6 ) ⁢ ⅆ x < ∞

M185
( ∇× F ) ⋅ k = z + 1

M186 M ⁢ M M M M

M187
ⅅ x x 2    ⅅ x ( x 2 )    ⅅ x ⁣ x ( x 2 )    ⅅ x 2 ( x 2 )    ⅅ x ⁣ y ( x 2 ⁢ y 3 )    ⅅ x s ⁣ y t ( x 2 ⁢ y 3 )

M188
5 24 ! x 6

M189
x + a y − 1 12.34 2 sin ⁡ θ 1

M190 0 1 1 0

M191 ( 0 − i i 0 )

M192 [ 1 0 0 − 1 ]

M193 | a b c d |

M194 ∥ 1 0 1 0 11 ∥

M195 1 2 3 4 5

M196
testing  sin ⁡ θ

M197 a ^ + b ˇ + c ˜ + d ´ + e ` + f ˘ + g ¯ + h + i ˚ + j ˙ + k ¨ + l ⃛ + m ⃜ + n →

M198 f ⁡ ( g ⁡ ( x ) ) = sin 3 ⁡ x 2 + sin ⁡ x 2 ⁢ sin ⁡ ( sin ⁡ x 2 )

M199 ( x 2 + 12 x 2 + 12 ) + 1234

M200
x = 1 not here x 2 merged y 1 jbm lowlife The end.

M201
x 2 + y 2 = z 2 − 1

M202
x 2 + y 2 = z 2 − 1 x + y 3 = z 3

M203
x 2 + y 2 = z 2 − 1 x + y 3 = z 3

M204
x 2 + y 2 = 1 x = 1 − y 2

M205
( a + b ) 2 = a 2 + 2 ⁢ a ⁢ b + b 2 ( a + b ) ⋅ ( a − b ) = a 2 − b 2

M206
First line of equation Middle line of equation Other middle line of equation Last line of equation

M207
L 1 = R 1    L 2 = R 2 L 3 = R 3    L 4 = R 4

M208 ( a + b ) 4 = ( a + b ) 2 ⁢ ( a + b ) 2 = ( a 2 + 2 ⁢ a ⁢ b + b 2 ) ⁢ ( a 2 + 2 ⁢ a ⁢ b + b 2 ) = a 4 + 4 ⁢ a 3 ⁢ b + 6 ⁢ a 2 ⁢ b 2 + 4 ⁢ a ⁢ b 3 + b 4

M209
x 2 + y 2 = 1 x = 1 − y 2    ( a + b ) 2 = a 2 + 2 ⁢ a ⁢ b + b 2 ( a + b ) ⋅ ( a − b ) = a 2 − b 2