Question

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

Answer 1

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:

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