Question

Help? Solve 2x^2 + 7x - 15 = 0 using the quadratic formula.

Answer 1

I got [31.25,-32.25].

Answer 2

\(\bf 2x^2 + 7x - 15 = 0 \\ \quad \\
x= \cfrac{ - b \pm \sqrt { b^2 -4ac}}{2a}\implies x= \cfrac{ - (7) \pm \sqrt { (7)^2 -4(2)(-15)}}{2(2)}\\ \quad \\
x= \cfrac{ - (7) \pm \sqrt { 49 +120}}{4}\implies x= \cfrac{ - (7) \pm \sqrt { 169}}{4}\implies x= \cfrac{ - 7 \pm 13}{4}\)

Answer 3

3/2 and - 5

Answer 4

So [1.5, -20]?

Answer 5

@jdoe0001

Answer 6

Oops, -5!

Answer 7

yes \(\bf x= \cfrac{ - 7 \pm 13}{4}\\ \quad \\
x =
\begin{cases}
\cfrac{ - 7 - 13}{4}\implies\cfrac{-20}{4}\implies& \bf -5\\ \quad \\
\bf \cfrac{ - 7 + 13}{4}\implies \cfrac{6}{4}\implies&\bf \cfrac{3}{2}
\end{cases}\)

Answer 8

Thanks!

Answer 9

yw

Answer 10

I realize now I put a in the place of -(b) instead of 7.

Answer 11

*2