Put the quadratics below into vertex form by completing the square. state the vertex.

Question

a) y=x^2 - 4x-21

Answer 1

y=x^2 - 4x-21
= (x^2 - 4x + 4 - 4) - 21
= ( (x-2)^2 - 4) - 21
= (x-2)^2 - 4 - 21
= (x-2)^2 - 25

take over