Which equation is equivalent to?

Question

asked May 1, 2020 223k views

1 Answer

Enpith · Answer 1 · 2020-05-05T14:45:28+0000

For this case we must find an equation equivalent to:

$\sqrt {x ^ 2 + 81} = x + 10$

We square both sides of the equation to eliminate the root:

x ^ 2 + 81 = (x + 10) ^ 2

We have by definition that:

(a + b) ^ 2 = a ^ 2 + 2ab + b ^ 2

So, rewriting the right side of the equation we have:

$x ^ 2 + 81 = x ^ 2 + 2 * 10 * x + 10 ^ 2\\x ^ 2 + 81 = x ^ 2 + 20x + 100$

ANswer:

Option D