Question

solve for x using quadratic formula x2+10x=9

Answer 1

how about this?

\[x^2+10x=9\]
\[(x+5)^2=9+5^2\]
\[(x+5)^2=34\]
\[x+5=\pm\sqrt{34}\]
\[x=-5\pm\sqrt{34}\]

Answer 2

quadratic formula is harder to use here because it forces you to have a denominator. if the "middle term" has an even coefficient it is much easier to complete the square, which is really all the formula does for you anyway

Answer 3

first you would have to write
\[x^2+10x-9=0\] then use
\[x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}\] with
\[a=1,b=10,=-9\] you would get
\[x=\frac{-10\pm\sqrt{136}}{2}\] and then you would have to simpify

Answer 4

simpify please

Answer 5

i did

Answer 6

when you simplify you get
\[x=-5\pm\sqrt{34}\]

Answer 7

ok

Answer 8

oh you mean how how do you simplify
\[x=\frac{-10\pm\sqrt{136}}{2}\]?

Answer 9

ya

Answer 10

i can show you if you like. you will get
\[-5\pm\sqrt{34}\] but you have to be careful

Answer 11

ok

Answer 12

first of all you have to take care of
\[\sqrt{136}\] is it
\[\sqrt{4\times 34}=2\sqrt{34}\] because the square root of 4 is 2

Answer 13

then you have
\[\frac{-10\pm2\sqrt{34}}{2}\] factor out a 2 to get
\[\frac{2(-5\pm\sqrt{34}}{2}\] then cancel to get
\[-5\pm\sqrt{34}\]

Answer 14

you can see why completing the square is easier here

Answer 15

ya

Answer 16

i don't have to do all that simplification at the end. get the answer in 4 easy steps

Answer 17

thanks

Answer 18

you can see the four steps at the top of this post. they are simpler than all this quadratic formula mes

Answer 19

yw