Question

Complete the square. Tutor confused me
y=2x^2+6x+2
->y=-2(x^2-3x)+2
(I'm not sure how or why he got 9/2 in this part)
->y=-2(x^2-3x+9/4)+2+9/2
Final answer: y=-2(x-3/2)^2+13/2
[this is for transformations and professor wants us to put it in standard form before we graph]

Answer 1

well since he subtracted 9/2 he added it cause he cant really change anything
-2 * 9/4 = -9/2 so you must add 9/2

Answer 2

how did it get from [x^2-3x+9/4] to [x-3/2]^2 not really sure how it was simplified

Answer 3

whenever you complete square the method is :
x^2 - 3x
so 3 is 2ab
in this case a = 1
b = ?
-3 = 2b
b = -3/2
now look at what happened :
a^2x^2 - abx + b^2
= (ax+b)^2
a =1 b = 3/2 -> (x -3/2)^2

Answer 4

Thank you =]