Question

Solve this quadratic equation using the quadratic formula.

x2 + 8x - 5 = 0

Answer 1

List your A,B,C values keeping this in mind
\[\huge~\rm~ax^2+bx+c=0\]

Answer 2

\[\frac{ -8\pm \sqrt{(8)^{2}-4(1)(5)} }{ 2(1) }\]

Answer 3

don't forget about the minus sign (negative) in front of that 5 :)

Answer 4

thanks

Answer 5

Perfect @gizmo25

Now simplify.
\[\frac{ -8 \pm \sqrt{64-20} }{ 2 }\]\[\frac{ -8 \pm \sqrt{44} }{ 2 }\]Oops; I was about to solve it all for you. Can you work it out from here?
Hint: Pull out what you can from the square root.

Answer 6

@GreenCat note that I just mentioned the negative
so it should be a 64 + 20 instead :)

Answer 7

oh yes; it is (-5).
Sorry.

Answer 8

I was working from Gizmo's equation.
@gizmo25 Remember to include the negative in "-5" there.

Answer 9

\[\frac{ -8 \pm \sqrt{64+20} }{ 2 }\]\[\frac{ -8 \pm \sqrt{84} }{ 2 }\]Here You go.

Answer 10

thanks :)