Question

Solve 8x^2+7x-15=-7... I got -8.09 and -5.91?? PLEASE HELP! thanks so much :)

Answer 1

Move the RHS to the LHS and simplify\[8 x^2+7 x-15+7=0 \]\[8 x^2+7 x-8=0 \]Solve the above for x using the quadratic formula:\[x=\frac{-b\pm \sqrt{b^2-4a c}}{2a}=\frac{-7\pm \sqrt{7^2-4(8)(-8)}}{2*8}=\frac{1}{16} \left(-7\pm \sqrt{305}\right) \]\[x\to \{0.654016,-1.52902\} \]