Question

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

Answer 1

Explanation:

Answer 2

For this case we have the following equation of the second degree:

`7x ^ 2 = 9 + x`

Rewriting:

`7x ^ 2-x-9 = 0`

The solutions will be given by the following equation:

`x = \frac {-b \pm \sqrt {b ^ 2-4 (a) (c)}} {2a}`

We have to:

`a = 7\\b = -1\\c = -9`

Substituting the values:

`x = \frac {- (- 1) \pm \sqrt {(- 1) ^ 2-4 (7) (- 9)}} {2 (7)}\\x = \frac {1 \pm \sqrt {(- 1) ^ 2 + 4 (7) (9)}} {2 (7)}`

Answer:

Option D