Two questions actually. Please only respond with step-by-step answers. Feel free to change the numbers, I just need to know how to do it...

1.) Factor Completely:
4a^2 + 81 - 36a

2.) In a right triangle, find the length of the side not given. b= 2 c= sqrt. 13

1 answer

1.) 4a^2 -36a + 81

What are factors of 81? (3 * 3 * 3 * 3)
What are factors of 4? (2 * 2)
What combination of these factors (or the whole number) can give you -36 for the middle term?

2.) Pythagorean theorem

a^2 + b^2 = c^2

a^2 + 4 = 13

Can you work it from here?