Question

Which equation is y = 9x2 + 9x – 1 rewritten in vertex form?
y = 9 (x + one-half) squared minus thirteen-fourths
y = 9 (x + one-half) squared minus 1
y = 9 (x + one-half) squared + five-fourths
y = 9 (x + one-half) squared minus five-fourths

Answer 1

y = 9(x + 1/2)^2 − 13/4

Work: y = 9x^2 + 9x − 1 = 9(x^2 + x) − 1 = 9[(x + 1/2)^2 − 1/4] − 1 = 9(x + 1/2)^2 − 9/4 − 1 = 9(x + 1/2)^2 − 13/4.