Question

solve the equations for all values of x by completing the square x^2+62=-16x

Answer 1

Answer:

$x = \sqrt{2} - 8\\x = -\sqrt{2} - 8$

Step-by-step explanation:

To complete the square, we first have to get our equation into $ax^2 + bx = c$ form.

First we add 16x to both sides:

$x^2 + 16x + 62 = 0$

And now we subtract 62 from both sides.

$x^2 + 16x = -62$

We now have to add $(\frac{b}{2})^2$ to both sides of the equation. b is 16, so this value becomes $(16\div2)^2 = 8^2 = 64$.

$x^2 + 16x + 64 = -62+64$

We can now write the left side of the equation as a perfect square. We know that x+8 will be the solution because $8\cdot8=64$ and $8+8=16$.

$(x+8)^2 = -62 + 64$

We can now take the square root of both sides.

$x+8 = \sqrt{-62+64}\\\\ x+8 = \pm \sqrt{2}$

We can now isolate x on one side by subtracting 8 from both sides.

$x = \pm\sqrt{2} - 8$

So our solutions are

$x = \sqrt{2} - 8\\x = -\sqrt{2} - 8$

Hope this helped!