Answer
$x=-3$
$x={\dfrac{5}{4}}$
Work Step by Step
$x=\dfrac{-b±{\sqrt {b^{2}-4ac}}}{2a}$ and $4x^{2}+7x-15=0$.Therefore, $a=4$,$b=7$ and $c=-15$:
Substitute the values:
$x=\dfrac{-7±{\sqrt {7^{2}-4(4)(-15)}}}{2(4)}$
=$\dfrac{-7±{\sqrt {49-(-240)}}}{8}$
=$\dfrac{-7± {\sqrt {289}}}{8}$
=$\dfrac{-7±17}{8}$
Separate the equation into plus and minus equations:
$x=\dfrac{-7-17}{8}=-3$
$x=\dfrac{-7+17}{8}={\dfrac{5}{4}}$
