If $x+2$ is a factor of $f(x)=2x^3-3x^2-4x+a$ , find the value of $a$ ?

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Answer 1 · 2018-02-28T18:19:59

$a=20$

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Write down the coefficient numbers in the first row in order of highest to lowest power and the factor.

$x+2 (x-m) m=-2$

Drag the first coefficient number down, $2xx(-2)=-4$ , write $-4$ under the next coefficient number, $-3+(-4)=-7$ , $(-2)xx(-7)=14$ , repeat...

We want the denominator to be zero, so

$a+(-20)=0$

$a=20$

Answer 2 · 2018-02-28T18:41:06

$a=20$

$"given "x+2" is a factor then "x=-2" is a zero"$

$rArrf(-2)=2(-2)^3-3(-2)^2-4(-2)+a=0$

$rArr-16-12+8+a=0$

$rArra=20$

If x+2x+2 is a factor of f(x)=2x^3-3x^2-4x+af(x)=2x^3-3x^2-4x+a , find the value of aa?