Question

Use substitution to write an equivalent quadratic equation. (3x + 2)2 + 7(3x + 2) – 8 = 0

Answer 1

the answer is the second choice. u^2+7u-8=0 where u=3x=2

Answer 2

we have

$(3x+2)^{2}+7(3x+2)-8=0$ --------> equation $1$

let's change of variable

$u=(3x+2)$ --------> equation $2$

substitute in the equation $2$ in equation $1$

$(u)^{2}+7(u)-8=0$

therefore

the answer is

$(u)^{2}+7(u)-8=0$