SOLUTION: solve by completing the square 9X^2 +18x-5 now i divide 9 into 9x^2 , 18x and -5 to get x^2 +2x -5/9 then i square of -5/9 to get -5/3 and i got stuck becaus

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: solve by completing the square 9X^2 +18x-5 now i divide 9 into 9x^2 , 18x and -5 to get x^2 +2x -5/9 then i square of -5/9 to get -5/3 and i got stuck becaus      Log On


   

Question 228018: solve by completing the square
9X^2 +18x-5

now i divide 9 into 9x^2 , 18x and -5 to get

x^2 +2x -5/9

then i square of -5/9 to get -5/3 and i got stuck because my book says that by squaring x ^2 +2 its suppose to equal to -1/3
anyone can give me a full break down why the answer to 9x^2 +18x=-5x is

-1/3, -5/3
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
9X^2 +18x-5
now i divide 9 into 9x^2 , 18x and -5 to get
x^2 + 2x - 5/9 = 0
:
x^2 + 2x + ___ = 5%2F9
:
Complete the square, divide the coefficient of 2 by 2 and square (2/2)^2 = 1
x^2 + 2x + 1 = 5%2F9 + 1; added 1 to both sides
:
x^2 + 2x + 1 = 5%2F9 + 9%2F9
:
(x + 1)^2 = 14%2F9
:
Find the square root of both sides
x + 1 = +/- sqrt%2814%2F9%29
:
Extract the square root of 1/9
x + 1 = +/- %281%2F3%29sqrt%2814%29
:
Two solutions
x = -1 - %281%2F3%29sqrt%2814%29
and
x = -1 + %281%2F3%29sqrt%2814%29
;
:
I know this is not what your book says, but that's what I get for this equation
It checked out on my Ti83