y= 3(2x + 1)^2 - 5. Please show all working out >.<
I wanted to solve for x, hence the topic. I tried it before , but I got (-1 + square root 15) /2, which was totally not the answer. That's why I wanted the steps, to show me how to get there. I know the answer, it's 0.145... and -1.145... I just need to know how to get round it.
$\displaystyle y = 3(2x + 1)^2 - 5$
$\displaystyle y + 5 = 3(2x + 1)^2$
$\displaystyle \frac{y + 5}{3} = (2x + 1)^2$
$\displaystyle \sqrt{ \frac{y + 5}{3} } = 2x + 1$
$\displaystyle \sqrt{ \frac{y + 5}{3} } - 1 = 2x$
$\displaystyle \frac{ \sqrt{ \frac{y + 5}{3} } - 1 }{2} = x$