Question

Solve. 9x2 – 21x + 15 = 0.

Answer 1

9x2 – 21x + 15 = 0
3(3x^2 - 7x + 5) = 0
3x^2 - 7x + 5 = 0

Use the quad formula and let a = 3, b = -7, c = 5

\[x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\]

Answer 2

I still don't understand how to do it? I sqaure 21 and get 441 - 540. What do I do now?