Question

Sarah thinks of a number. She squares it, adds the square root of 64, divides it all by the cube root of 512, and then finally she adds 8 quarters. Her answer is 4. What number did she start with?

Answer 1

~3

Explanation:

Let x be unknown number

X^2 + square root of 8/cube root of 512 + 8/4=4

X^2 +8/8 +2 = 4

Multiply through by 8 to get rid of denominator

X^2 + 8 + 16 = 32

X^2 + 24 = 32

X^2= 32 - 24

X^2= 8

Find the square root of both sides

X= 2.828427...

X=~3