Question 1180267

Consider the quadratic equation y=-10 x^2 - 60 x + 8.
Complete the square to express the quadratic in standard form y=a (x-h)^2 +k.

a= 

h=

k = 
<pre>His answer is WRONG, so: {{{cross(highlight(y=-10(x+3)^2-82))}}}
Furthermore, the more a person can STEER CLEAR of fractions, the better off he/she may be.
{{{matrix(1,3, y, "=", - 10x^2 - 60x + 8)}}}
{{{matrix(1,3, y, "=", - 10(x^2 + 6x) + 8)}}} -------- Factoring out - 10 on x<sup>2</sup> and x to make coefficient on x<sup>2</sup>, + 1
{{{matrix(1,3, y, "=", - 10(x^2 + 6x + ((1/2) * b)^2 - ((1/2) * b)^2) + 8)}}} ----- Taking ½ of b ON x, squaring the result, then adding to/subtracting from right-side
{{{matrix(1,3, y, "=", - 10(x^2 + 6x + ((1/2) * "+ 6")^2 - ((1/2) * "+ 6")^2) + 8)}}} --- ADDING and SUBTRACTING, - 10(½ * + 6)<sup>2</sup>
{{{matrix(4,3, y, "=", - 10(x^2 + 6x + ("+ 3")^2  -  ("+ 3")^2) + 8, y, "=", - 10(x^2 + 6x + ("+ 3")^2  -  9) + 8, y, "=", - 10(x^2 + 6x + ("+ 3")^2)  -  10(- 9) + 8, y, "=", - 10(x + 3)^2 + 90 + 8)}}}
Correct answer: {{{highlight_green(matrix(1,3, y, "=", - 10(x + 3)^2 + 98))}}}