Question

Solve for x in the equation x2+20x+100=36

Answer 1

The answer is:
$x = - 64 \div 22 = -2.909091$
But if x2 was supposed to be x^2 then the answer is:
$x = - 4.-16$

Answer 2

Answer:

x = -4 and x = -16.

Step-by-step explanation:

We have the equation,

$x^{2}+20x+100=36$

i.e. $x^{2}+20x+64=0$

As the solution of a quadratic equation $ax^{2}+bx+c=0$ is given by $x=\frac{-b\pm \sqrt{b^{2}-4ac}}{2a}$.

On comparing, a = 1, b = 20, c = 64.

So, the solution is,

$x=\frac{-20\pm \sqrt{(20)^{2}-4\times 1\times 64}}{2a\times 1}$.

i.e. $x=\frac{-20\pm \sqrt{400-256}}{2}$.

i.e. $x=\frac{-20\pm \sqrt{144}}{2}$.

i.e. $x=\frac{-20\pm 12}{2}$.

i.e. $x=\frac{-20+12}{2}$ and $x=\frac{-20-12}{2}$.

i.e. $x=\frac{-8}{2}$ and $x=\frac{-32}{2}$.

i.e. x = -4 and x = -16

Thus, the solution of the given equation is x = -4 and x = -16.