Question

What number you multiple without changing the value

Answer 1

The given expression is

`4r^2+15r+7=-1`

First, we add 1 on each side

`\begin{gathered} 4r^2+15r+7+1=-1+1 \\ 4r^2+15r+8=0 \end{gathered}`

Then, we use the quadratic formula

`r=\frac{-b\pm\sqrt[]{b^2-4ac^{}}}{2a}`

Where a = 4, b = 15, and c = 8.

`\begin{gathered} r=\frac{-15\pm\sqrt[]{15^2-4\cdot4\cdot8}}{2\cdot4}=\frac{-15\pm\sqrt[]{225-128}}{8} \\ r=\frac{-15\pm\sqrt[]{97}}{8} \end{gathered}`

Then, we rewrite the equation into two solutions

`\begin{gathered} r_1=\frac{-15+\sqrt[]{97}}{8} \\ r_2=\frac{-15-\sqrt[]{97}}{8} \end{gathered}`