Question

Find the value of b so that -2 is a root of 3x³+bx²+5x-27=0

Answer 1

Answer:

The answer is $b=\frac{61}{4}$

Step-by-step explanation:

Since $-2$ is a root of $3x^3+bx^2+5x-27=0$

So -2 must satisfy this cubic equation

$\Rightarrow 3(-2)^3+b(-2)^2+5(-2)-27=0\\\Rightarrow 3(-8)+b(4)-10-27=0\\\Rightarrow -24+4b-10-27=0\\\Rightarrow 4b-61=0\\\Rightarrow 4b=61\Rightarrow b=\frac{61}{4}$