Question

Solve. 3x2 = –21x – 15

Answer 1

Using quadratic formula

Answer 2

3x^2+21x+15

a=3, b=21, c=15

-b±√b^2-4ac/2a

plug in and solve.

Answer 3

OK.

Answer 4

I don't know whtat the b^2 - 4(a)(c) is

Answer 5

-b±√b^2-4ac/2a is the quadratic formula.

Answer 6

Yeah, I know but I don't know what the answer is for b^2 - 4(a)(c)

Answer 7

lets plug in, a, b and c.

-(21)±√21^2-4(3)(15)/2(3)

Answer 8

I got 126 inside the radical

Answer 9

261*

Answer 10

You are correct.

Answer 11

Okay, then what do I do?

Answer 12

This website should give you some clarification on solving the quadratic formula.

http://www.purplemath.com/modules/quadform.htm

Answer 13

Thanks.