Evaluate
\left(7x-y\right)\left(7y-3x\right)
Expand
-21x^{2}+52xy-7y^{2}
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4x^{2}+12xy+9y^{2}-\left(4y-5x\right)^{2}
Use binomial theorem \left(a+b\right)^{2}=a^{2}+2ab+b^{2} to expand \left(2x+3y\right)^{2}.
4x^{2}+12xy+9y^{2}-\left(16y^{2}-40yx+25x^{2}\right)
Use binomial theorem \left(a-b\right)^{2}=a^{2}-2ab+b^{2} to expand \left(4y-5x\right)^{2}.
4x^{2}+12xy+9y^{2}-16y^{2}+40yx-25x^{2}
To find the opposite of 16y^{2}-40yx+25x^{2}, find the opposite of each term.
4x^{2}+12xy-7y^{2}+40yx-25x^{2}
Combine 9y^{2} and -16y^{2} to get -7y^{2}.
4x^{2}+52xy-7y^{2}-25x^{2}
Combine 12xy and 40yx to get 52xy.
-21x^{2}+52xy-7y^{2}
Combine 4x^{2} and -25x^{2} to get -21x^{2}.
4x^{2}+12xy+9y^{2}-\left(4y-5x\right)^{2}
Use binomial theorem \left(a+b\right)^{2}=a^{2}+2ab+b^{2} to expand \left(2x+3y\right)^{2}.
4x^{2}+12xy+9y^{2}-\left(16y^{2}-40yx+25x^{2}\right)
Use binomial theorem \left(a-b\right)^{2}=a^{2}-2ab+b^{2} to expand \left(4y-5x\right)^{2}.
4x^{2}+12xy+9y^{2}-16y^{2}+40yx-25x^{2}
To find the opposite of 16y^{2}-40yx+25x^{2}, find the opposite of each term.
4x^{2}+12xy-7y^{2}+40yx-25x^{2}
Combine 9y^{2} and -16y^{2} to get -7y^{2}.
4x^{2}+52xy-7y^{2}-25x^{2}
Combine 12xy and 40yx to get 52xy.
-21x^{2}+52xy-7y^{2}
Combine 4x^{2} and -25x^{2} to get -21x^{2}.
Examples
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{ x } ^ { 2 } - 4 x - 5 = 0
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4 \sin \theta \cos \theta = 2 \sin \theta
Linear equation
y = 3x + 4
Arithmetic
699 * 533
Matrix
\left[ \begin{array} { l l } { 2 } & { 3 } \\ { 5 } & { 4 } \end{array} \right] \left[ \begin{array} { l l l } { 2 } & { 0 } & { 3 } \\ { -1 } & { 1 } & { 5 } \end{array} \right]
Simultaneous equation
\left. \begin{cases} { 8x+2y = 46 } \\ { 7x+3y = 47 } \end{cases} \right.
Differentiation
\frac { d } { d x } \frac { ( 3 x ^ { 2 } - 2 ) } { ( x - 5 ) }
Integration
\int _ { 0 } ^ { 1 } x e ^ { - x ^ { 2 } } d x
Limits
\lim _{x \rightarrow-3} \frac{x^{2}-9}{x^{2}+2 x-3}