Question

Does anyone know how he got from step 1 to step 2??????????

Answer 1

9514 1404 393

Step-by-step explanation:

Both sides of the equation are squared.

`(x-12)/(4)=√(x) \qquad\text{given}\\\\ \left((x-12)/(4)\right)^2=x \qquad\text{square both sides}\\\\ \left((x)/(4)-3\right)^2=x \qquad\text{divide out the fraction}\\\\ (x^2)/(4^2)-(6)/(4)x+9=x \qquad\text{$(a-b)^2=a^2-2ab+b^2$}\\\\(x^2)/(16)-(5x)/(2)+9=0 \qquad\text{subtract $x$}`

I like this better without fractions, so would multiply by 16 at this point (or earlier).

x^2 -40x +144 = 0

(x -36)(x -4) = 0

x = 4 or 36 . . . . . . x = 4 is extraneous

The solution is x = 36.