SOLUTION: Okay well I have broken down the equation of Y=-5x^2+30x-36 Down to Y=-5(x^2-6x)-36 I'm trying to break it down to standard form. Then it's telling me to recall that be cons

Question 869742: Okay well I have broken down the equation of
Y=-5x^2+30x-36
Down to
Y=-5(x^2-6x)-36
I'm trying to break it down to standard form.
Then it's telling me to recall that be constant term in a perfect square is the square of half of the coefficient of the linear term therefore 9 is added inside the parentheses to form a perfect square
Leaving x^2-6x+9
My question is where exactly did the 9 come from?
Found 2 solutions by mananth, josgarithmetic:
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
Y=-5x^2+30x-36
Y=-5(x^2-6x)-36

Recall (a-b)^2=a^2-2ab+b^2
we have a^2-2ab
which is
x^2-(2)(3)x
adding 9 will make it a perfect square
x^2-(2)(3)(3)+9
we have added 9 so we have to subtract 9
x^2-6x+9-9
Finally we have
y= -5(x^2-6x+9-9) -36
y=-5((x-3)^2-9)-6^2

Answer by josgarithmetic(39620) (Show Source): You can put this solution on YOUR website!
Study these two lessons:

This show what Completing the Square means
and
How to use Completing the Square for a quadratic equation
RELATED QUESTIONS
CAN SOMEONE PLEASE HELP ME AND SHOW ME HOW TO WORK OUT THESE PROBLEMS.I IF U BREAK IT... (answered by cyeannakis,stanbon)
Hi there, I have a question about solving for the LCM (Least common multiple) of two... (answered by josgarithmetic)
I need help finding the vertex of the parabola... I'm just not sure how to break this... (answered by Alan3354)
What are the solutions for the system of equations for x^2+y^2=36 y=x+2. I tried using... (answered by Fombitz)
I know have a problem and I dont know how to break the problem down (x^2-x-6)/(x^2-4) (answered by jim_thompson5910)
I need to multiply the fraction -3a^2b/35a^5 x 35a^5 / 9b^4= I have it broken down... (answered by stanbon)
I have been trying to simplify the {{{sqrt(363)}}}, by taking 36 and breaking it down to... (answered by scott8148,Edwin McCravy)
Factor completely. x^2 - 13x + 36 I get (x - 9) (x-4) by looking at it - but to... (answered by mszlmb)
f(x)=4x^4-24x^3+35x^2+6x-9 I have to graph this polynomial function. Minimum/maximums do (answered by Alan3354)