Evaluate
x\left(8-21x-5x^{2}\right)
Expand
8x-21x^{2}-5x^{3}
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8x-8x^{3}-\left(x-7\right)\left(-3\right)x^{2}
Use the distributive property to multiply 8x by 1-x^{2}.
8x-8x^{3}-\left(-3x+21\right)x^{2}
Use the distributive property to multiply x-7 by -3.
8x-8x^{3}-\left(-3x^{3}+21x^{2}\right)
Use the distributive property to multiply -3x+21 by x^{2}.
8x-8x^{3}+3x^{3}-21x^{2}
To find the opposite of -3x^{3}+21x^{2}, find the opposite of each term.
8x-5x^{3}-21x^{2}
Combine -8x^{3} and 3x^{3} to get -5x^{3}.
8x-8x^{3}-\left(x-7\right)\left(-3\right)x^{2}
Use the distributive property to multiply 8x by 1-x^{2}.
8x-8x^{3}-\left(-3x+21\right)x^{2}
Use the distributive property to multiply x-7 by -3.
8x-8x^{3}-\left(-3x^{3}+21x^{2}\right)
Use the distributive property to multiply -3x+21 by x^{2}.
8x-8x^{3}+3x^{3}-21x^{2}
To find the opposite of -3x^{3}+21x^{2}, find the opposite of each term.
8x-5x^{3}-21x^{2}
Combine -8x^{3} and 3x^{3} to get -5x^{3}.
Examples
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{ x } ^ { 2 } - 4 x - 5 = 0
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Matrix
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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
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