Question

Which equation shows the quadratic formula used correctly to solve 7x^2 = 9 + x for x?

Answer 1

Answer:

Step-by-step explanation:

We must rewrite 7x^2 = 9 + x in standard form first:  7x^2 - x - 9 = 0.

The coefficients are 7, -1 and -9, and so the discriminant b^2 - 4ac is

(1)^2 - 4(7)(-9) = 253.

The roots are:

       -(-1) ± √253           1 ± √253

x = --------------------- = --------------------

              2(7)                       14