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21+9x-7x^{2}
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21+9x-7x^{2}
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21-4x\left(2x-1\right)-\left(x\left(-x\right)-5x\right)
Use the distributive property to multiply x by -x-5.
21-4x\left(2x-1\right)-x\left(-x\right)-\left(-5x\right)
To find the opposite of x\left(-x\right)-5x, find the opposite of each term.
21-4x\left(2x-1\right)+xx-\left(-5x\right)
Multiply -1 and -1 to get 1.
21-4x\left(2x-1\right)+x^{2}-\left(-5x\right)
Multiply x and x to get x^{2}.
21-4x\left(2x-1\right)+x^{2}+5x
The opposite of -5x is 5x.
21-8x^{2}+4x+x^{2}+5x
Use the distributive property to multiply -4x by 2x-1.
21-7x^{2}+4x+5x
Combine -8x^{2} and x^{2} to get -7x^{2}.
21-7x^{2}+9x
Combine 4x and 5x to get 9x.
21-4x\left(2x-1\right)-\left(x\left(-x\right)-5x\right)
Use the distributive property to multiply x by -x-5.
21-4x\left(2x-1\right)-x\left(-x\right)-\left(-5x\right)
To find the opposite of x\left(-x\right)-5x, find the opposite of each term.
21-4x\left(2x-1\right)+xx-\left(-5x\right)
Multiply -1 and -1 to get 1.
21-4x\left(2x-1\right)+x^{2}-\left(-5x\right)
Multiply x and x to get x^{2}.
21-4x\left(2x-1\right)+x^{2}+5x
The opposite of -5x is 5x.
21-8x^{2}+4x+x^{2}+5x
Use the distributive property to multiply -4x by 2x-1.
21-7x^{2}+4x+5x
Combine -8x^{2} and x^{2} to get -7x^{2}.
21-7x^{2}+9x
Combine 4x and 5x to get 9x.
Examples
Quadratic equation
{ x } ^ { 2 } - 4 x - 5 = 0
Trigonometry
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}