Question

Use factoring to find the zeros of y=x^2+4x-21 and the equation of axis of symmetry ?

Answer 1

Think of two numbers that multiply to make -21, and add to make +4 at the same time.

Answer 2

I already know its 3 and 7 but I dont know how to write the answer out .

Answer 3

thats the hardest part, figuring out those numbers. because of the signs of the 21 and 4, the two numbers have to be -3 and +7 . So the final answer would be:
\[(x-3)(x+7)\]

Answer 4

Thats basically how it goes, you figure out what the two numbers are, and then just make a product using them.

Answer 5

Does x equal that or y ?

Answer 6

it would be y = (x - 3)(x + 7)