quadratic formula

**shortd333** · May 23rd 2007, 03:27 PM

okay, i have this question and i have to find the roots/x-intercepts/zeros w/e of -4xsquared+5x+7 and i can't figure it out because the answer using the quadratic formula is different then the ones given (its multiple choice) can anyone help me? ... i dont know if this makes any sense though ...

**Jhevon** · May 23rd 2007, 03:39 PM

Originally Posted by shortd333

okay, i have this question and i have to find the roots/x-intercepts/zeros w/e of -4xsquared+5x+7 and i can't figure it out because the answer using the quadratic formula is different then the ones given (its multiple choice) can anyone help me? ... i dont know if this makes any sense though ...

Let's try the quadratic formula one more time:

$-4x^2 + 5x + 7 = 0$

By the quadratic formula:

$\Rightarrow x = \frac {-5 \pm \sqrt {5^2 - 4(-4)(7)}}{2(-4)}$

$\Rightarrow x = \frac {-5 \pm \sqrt {137}}{-8}$

$\Rightarrow x = \frac {5}{8} \pm \frac { \sqrt {137}}{8}$

what did the answers look like?

Thread: quadratic formula

LinkBack

Thread Tools

Display