1. ## algebra help plz

find the x intercepts of
y=2x^2-8x-7
using completing the square technique

Find x intercepts of
y=3x^2-9x+5

2. ## Ok

Originally Posted by gumi
find the x intercepts of
y=2x^2-8x-7
using completing the square technique

Find x intercepts of
y=3x^2-9x=5
We would have $\displaystyle 2(x-2)2-15=0$...solving for x we get $\displaystyle x=\frac{\pm{\sqrt{30}+4}}{2}$

and for the second one just use the quadratic formula $\displaystyle x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$

3. Originally Posted by gumi
find the x intercepts of
y=2x^2-8x-7
using completing the square technique

Find x intercepts of
y=3x^2-9x=5
First please note that the x-intercepts of the quadratic function are the roots of the corresponding quadratic equation. So for these two questions:

1) solve x for 2x^2-8x-7=0 using completing square technique
$\displaystyle 2(x^2-4x+4)-7=8\Rightarrow 2(x-2)^2=15\Rightarrow x=2\pm \frac{\sqrt{30}}{2}$

Roy

4. ## Ok

Originally Posted by roy_zhang
First please note that the x-intercepts of the quadratic function are the roots of the corresponding quadratic equation. So for these two questions:

1) solve x for 2x^2-8x-7=0 using completing square technique
$\displaystyle 2(x^2-4x+4)-7=8\Rightarrow 2(x-2)^2=15\Rightarrow x=2\pm \frac{\sqrt{30}}{2}$

Roy
What was wrong with my completing the square's?

5. Originally Posted by Mathstud28
What was wrong with my completing the square's?
Nothing wrong there.

Roy

6. ## Oh

Originally Posted by roy_zhang
Nothing wrong there.

Roy
were you jsut going through the motions for didactic purposes?

7. Originally Posted by Mathstud28
were you jsut going through the motions for didactic purposes?
No, I think you are too sensitive here. When I were typing my original response, I saw you just post your reply and I don't want to retype the quadratic formula , this is why i just type please see your comment for part (2). I have no intention to imply that your comment on (1) is not correct.

We are all here to learn and help.

Roy

8. ## Haha

Originally Posted by roy_zhang
No, I think you are too sensitive here. When I were typing my original response, I saw you just post your reply and I don't want to retype the quadratic formula , this is why i just type please see your comment for part (2). I have no intention to imply that your comment on (1) is not correct.

We are all here to learn and help.

Roy
I am sorry I didnt intend to sound angry or upset...I was just wondering