1. 8 + 7x =2x²

Question

I used my calculator to graph this and got
x is about 4.41 and -.904

2. 1/3x² - 15 = 0

Again, I graphed on my calculator and got x is about 6.70 and -6.70

Are these answers accurate and is there another way to solve?

Answer 1

1. x = (1/4)[7 +/- sqrt(49 + 64)]
= 4.408 or -0.9075

2. (1/3)(x^2 -45)= 0
(x+sqrt45)(x-sqrt45) = 0
x = +/-sqrt(45)= +/- 6.708