#### Answer

x=-$\frac{5}{2}$ or $\frac{3}{2}$

#### Work Step by Step

Rewrite the equation so it is in standard form.
4x(x+1)=15
4x$^2$+4x=15
4x$^2$+4x-15=0
Factor the trinomial.
(2x+5)(2x-3)=0
Set each variable factor as equal to zero and then isolate the variable to find the solutions.
2x+5=0 or 2x-3=0
2x=-5 or 2x=3
x=-$\frac{5}{2}$ or x=$\frac{3}{2}$
Enter the equation into your graphing utility to observe that the graph crosses the x-axis at -$\frac{5}{2}$ and $\frac{3}{2}$