Question

I applied u substitution, but I don't know what to do next. HELP!

Answer 1

I know the u substitution ends up being u^2+8u+11=0
What do I do next?

Answer 2

try to factor,
if its not possible, quadratic formula is always there

Answer 3

I feel retarded. I got factoring and the quadratic formula mixed up. :(
Thank you for your help though. :)

Answer 4

haha np :) we cannot factor this, so we nneed to use quadratic formula...

Answer 5

This is what I've done, but my result doesn't match any of the answers. Am I doing something wrong?
\[-8\pm \sqrt{64-4(1)(11)}/2\]
\[-8\pm \sqrt{64-44} /2\]
\[-8\pm \sqrt{20} /2\]
\[-4\pm \sqrt{10}\]

Answer 6

small mistake in the last step

Answer 7

\[\large \dfrac{-8 \pm\sqrt{20}}{2}\]

Answer 8

\[\large \dfrac{-8 \pm\sqrt{4 \times 5}}{2}\]

Answer 9

\[\large \dfrac{-8 \pm2\sqrt{5}}{2}\]

Answer 10

\[\large u = 4 \pm \sqrt{5}\]

Answer 11

substitute back u = 2x+3, and solve x

Answer 12

\[\large 2x+3 = 4 \pm \sqrt{5}\]

Answer 13

\[\large x = ?\]

Answer 14

I apologize for the late response. I was away from the computer for a while.
and Oh okay I see now.
\[-7\pm \sqrt{5} /2\]

Answer 15

Thank you for your help. :)