Question

Solve 2x^2 - 7x - 15 = 0.
a, (3/2,-5)
b (-3/2,5)
c ()

Answer 1

{-3/2, 5} would be the right choice

Answer 2

For this case we must solve the following quadratic equation:

`2x ^ 2 -7x -15 = 0`

We must apply the following formula:

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

We have to:

`a = 2\\b = -7\\c = -15`

Substituting we have:

`x = \frac {- (- 7) \pm \sqrt {(- 7) ^ 2-4 (2) (- 15)}} {2 (2)}\\x = \frac {7 \pm \sqrt {49 + 120}} {4}\\x = \frac {7 \pm \sqrt {169}} {4}\\x = \frac {7 \pm13} {4}`

Thus, the solutions are:

`x_ {1} = \frac {7 + 13} {4} = \frac {20} {4} = 5\\x_ {2} = \frac {7-13} {4} = \frac {-6} {4} = - \frac {3} {2}`

ANswer:

`x_ {1} = 5\\x_ {2} = - \frac {3} {2}`