math
posted by james on .
Complete the square to find the vertex of each quadratic function. State the vertex. (10 marks)
A) f(x) = x2 + 8x – 3
B) f(x) = x2 – 5x + 8
C) f(x) = 2x2 – 12x + 1
D) f(x) = 3x2 + 2x – 5

I will do one, you do the others.
You will learn how to do these only by doing lots of them
c)
f(x) = 2x^2  12x + 1
= 2(x^2  6x + ..... ) + 1
= 2(x^2  6x + 9  9 ) + 1
= 2( (x3)^2  9) + 1
= 2(x3)^2  18 + 1
= 2(x3)^2  17
vertex is (3, 17)