Algebra 2 review question...help!!!?

Question

Ok, so NO I am not a cheater, & I've worked on this for like 30 minutes & I simply can NOT get it, I'm having like a mental block or something. Well here's the problem. & p.s. I'm supposed to complete the square...

3(x^2) -6x + 7 = x^2 + 3x -x(x+1) + 3

which I simplified to

3(x^2) - 8x - 10 = 0

so then I did 3(x^2) - 8x = 10

then

x^2 - (8x/3) = 10/3

HELP!!! PLEASE!!!!

I know it's an easy question, but I'm having like a major mental block....

thanks =)

Answer 1

Remember when you move part of the equasion to the other side the +/- changes!

your +7 would change to +4 because you moved the +3 over!

you should have 3x^2 -8x +4=0

use the quadratic formula to solve

=)

Answer 2

It should have been 3x^2-8x-4=0. You added 3 instead of subtracting it.

Then we can add 4 over.

3x^2-8x=4

Factor out a 3

3(x^2-(8/3)x)=4

Divide (8/3) by 2 and square the result.

3(x^2-(8/3)x+16/9)=4

We now have to take into account the fact that we really added 3(16/9) to the left side of the equation, so we have to add it to the right side.

3(x^2-(8/3)x+16/9)=4+(16/3)

When we divided 8/3 by 2, we found the number that goes in the parentheses on the left side.

3(x-4/3)^2=28/3

Then if you need the vertex subtract 28/3 back over and it would be:

(4/3, -28/3)

Answer 3

3(x^2) - 8x + 4 = 0

Subtract three from both sides.

Don't use quad formula like the moron who posted below. Factoring will suffice.

Don't listen to the other moron either. Just do (3x-2)(x-2) = 0

3x-2=0

3x=2

x= 3/2, x = 2

Answer 4

Chill, have a beer and go out for a pizza!

If this is your only question, then you are doing well, and will do well at university also.

When your instructor does it, you will say, OF COURSE, and ace the next test.

Answer 5

3(x^2)-6x+7= x^2=3x-x(x+1)+3

you expand the bracket:

3x^2-6x+7  = x^2+3x-x^2-x+3

then you simplify to:

3x^2-6x+7  = x^2-x^2+3x-x+3

and then....

3x^2-6x+7  = 2x+3

and then you move 7...

3x^2-6x      =2x+3-7

and it becomes...

3x^2-6x      =2x-4

and then...

3x^2+4       =2x+6x

so its...

3x^2+4       =8x

sorry i kinda stuck there

dunno if i got it right

good luck !

Answer 6

you made a mistake

when you simplified it to

3(x^2)-8x-10=0

its 3(x^2)-8x+4=0

you know when you send the 3 over it turns negative..so it positive 7 -3=4 :)

so its