4 + (18 - 3 + 9) = 28
80399375
(30+2) - (45-23) = 8
expand (x-1/x)^2
DF = 8x - 12
FH = x + 3
FH = ½DF
DF = 2FH
FH = 2x + 6
8x - 12 = 2x + 6
8x - 2x = 6 + 12
6x = 18
x = 3
$\sqrt{462}$
dom F(X)=2 X+X^(2)
240÷400
(-27)^(1/3)
81^(1/2)
