# How do you solve -2k^2=-162?

Aug 18, 2016

$k = - 2 , \mathmr{and} k = + 2$

#### Explanation:

In solving a quadratic equation we usually make it = 0. However, in this case there is no term $x$, so we can use it in this form.

Isolate the variable.

$- 2 {k}^{2} = - 162 \text{ } \div - 2$

${k}^{2} = 81 \text{ find square root}$

$k = \pm \sqrt{81}$

$k = 9 \mathmr{and} k = - 9$

Another method....

$- 2 {k}^{2} + 162 = 0 \text{ } \div - 2$

${k}^{2} - 81 = 0 \text{ factorise}$

$\left(k + 2\right) \left(k - 2\right) = 0$
Each factor can be 0.

$k = - 2 , \mathmr{and} k = + 2$