CPM Homework Help : A2C Problem 7-84

Use the correct method from problem 7-83 to change each of the following equations to graphing form. Then, without graphing, find the vertex and equation of the line of symmetry for each.

$y = 2x^{2} − 8x + 7$
Hint (a):
Complete the square to find the equation.
$y = 2\left(x^{2} − 4x + 4\right) + 7 − 8$
More Help (a):
Use $y = a\left(x − h\right)^{2} + k$ and $\left(h, k\right)$ to find the vertex and axis of symmetry.
Partial Answer 1(a):
$y = 2\left(x − 2\right)^{2} − 1$
Partial Answer 2(a):
vertex: $\left(2, −1\right)$
axis of symmetry: $x = 2$

$y = 5^{2} − 10x − 7$
Hint (b):
See part (a).
Answer (b):
$y = 5\left(x − 1\right)^{2} − 12$
vertex: $\left(1, −12\right)$
axis of symmetry: $x = 1$