Step-by-step explanation:
f²-6f = -1
Add 9 both sides
f²-6f + 9 = -1+9 = 8
f²-6f+3² =8
f²-2*3f + 3² = 8
Now by (a²+b²+2ab) = (a+b)²
(f-3)²=8
f-3 = ±√8 Root both sides
f = ±√8+3 (Shift)i.e. -√8+3 or. √8+3
