Solving equation (x divided by 4) ^ 2 + (20-x) divided by the square of 4 = 17

Solving equation (x divided by 4) ^ 2 + (20-x) divided by the square of 4 = 17

Is your formula like this:
(x/4)²+[(20-x)/4]²=17
(x/4)²+[(20-x)/4]²+2(x/4) [(20-x)/4]=17+2(x/4) [(20-x)/4]
[x/4+(20-x)/4] ²=17+x(20-x)/8
25=17+x(20-x)/8
x(20-x)=64
x²-20x+64=0
(x-16)(x-4)=0
x1=16,x2=4