Choose a reasonable method for solving the equation. Round your answers to three decimal places. $$7 x ^ { 2 } + 8 x = 15$$
A) $x = \frac { 1 } { 7 } , x = - \frac { 1 } { 15 }$
B) $x = 1$
C) $x = - \frac { 7 } { 15 }$
D) $x = - \frac { 15 } { 7 } , x = 1$
E) no real-number solution

Question

Quizplus · Accepted Answer

The equation can be rearranged to $7x^2+8x-15=0$, which is a quadratic equation that can be factored as $(7x-15)(x+1)=0$. Therefore, the solutions are $x=-\frac{15}{7}$ and $x=-1$. Rounded to three decimal places, $x=-2.143$ and $x=-1.000$, respectively. Thus, the best choice is D, which includes both solutions rounded to three decimal places.

Choose a Reasonable Method for Solving the Equation 7x2+8x=157 x ^ { 2 } + 8 x = 157x2+8x=15

Choose a Reasonable Method for Solving the Equation $7 x ^ { 2 } + 8 x = 15$