help with math homework?

Question

solve by completing the square
9x^2-18x+3
(9x squared minus 18x plus 3)

also solve vy quadratic equation
-x^2+2x+2......okay the answer I got for this one is .............. one plus or minus negative one times square root of 3.....but the answer in the book says one plus or minus square root of 3...close but not exact

Answer 1

9x^2 - 18x + 3
= (9x^2 - 18x) + 3
= 9(x^2 - 2x) + 3
Divide the coefficient of x by 2, square it and then add and subtract it inside the parentheses
= 9(x^2 - 2x + 1 - 1) + 3
= 9(x^2 - 2x + 1) - 9 + 3
= 9(x-1)^2 - 6

9(x-1)^2 - 6 = 0
Add 6 to each side
9(x-1)^2 = 6
Divide by 9
(x-1)^2 = 6/9
(x-1)^2 = 1/3
Take the square root (sqrt) of each side
x - 1 = +/- sqrt(1/3)
x = 1 + sqrt(1/3) or x = 1 - sqrt(1/3)
You may need to rationalize sqrt(1/3), but I will leave that to you.

one plus or minus negative one times sqrt(3) is the same thing as 1 plus or minus sqrt(3).
The second way is just a simpler way of writing it.

Answer 2

Let me start by identifying "+/-" as "plus or minus" and the fractional exponent "^(1/2)" as the "square root."

a) 9x^2 - 18x + 3
= x^2 - 2x + 1/3
x^2 - 2x = -1/3
(x-1)^2 = 2/3
x-1 = +/- (2/3)^(1/2)
x = 1 +/- ((6)^(1/2)/3)
x = (3 +/- (6)^(1/2))/3

b) a = -1, b = 2, c= 2

-2 +/- (4 - (-8))^(1/2)/ -2
= 1 +/- (3)^1/2

the reason the negative goes away from the radical because +/- becomes -/+, which, in reality, is the same thing.

Answer 3

For the first part:
9x^2 - 18x + 3
x^2 - 2x + 1/3
x^2 + (-2/2)^2 - (-2/2)^2 + 1/3
(x-1)^2 - 1 + 1/3
(x-1)^2 - 2/3

To get your answer same as in the book, you need to change the equation like so:
x^2 - 2x - 2
Then work out the answer as you did before.
Both equations are the same by the way.

Answer 4

the first is like this-
9x.2-18x¨[ ]=-3
9x.2-18x+81=-3+81
2.'(3x+9).2=2.'(78)
3x+9= -+(you understand me)(2´.´78)
x1=-3+9+2.´78=6+(2.´78)
x2=-3+9-(2.´78)=6-(2.´78)

the other is in this way.
the other theres an error because the cuadratic root is -4
like this__x=-2+-(2.´-4)
_________
2

Answer 5

i got the same result for the second one
-x^2+2x+2
-ax^2 +bx +c

[-b +-square root of (b^2 -4(a)(c)]/2a

(-2 +-square root of (4 +8))/-2

Answer 6

i dont know much about math but you can go to google and type in math help or go to your teacher with questions you should really do this your self beacuse you learn that way better if you realy dont know get a tutore or ask for help for you can do it for your own !!!
God bless!!!

Answer 7

You dropped a sign somewhere in your figures. I did that all the time in algebra.

Answer 8

Um...great question....

Answer 9

omg idk what the heck that is u must be in high school or something becasue im only in middle school

Answer 10

i don't know