The product of $a+3$ and $-2a^2+15a+6$ is $-2a^3+xa^2+51a+18$ . What is the value of $x$ ?

Question

3174 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-06-16T21:20:54

$x = 9$

The method here is to equate the coefficients.
Find the product and then compare the like terms:

$(a+3)(-2a^2 + 15a +6)$

$=-2a^3 +15^2 + 6a - 6a^2+45a +18$

$=-2a^3 +9a^2 + 51a +18 " compare this with"$
$=-2a^3 +xa^2 + 51a +18$

It is clear that $x = 9$

The product of a+3a+3 and -2a^2+15a+6-2a^2+15a+6 is -2a^3+xa^2+51a+18-2a^3+xa^2+51a+18. What is the value of xx?