JAMB - Mathematics (1987 - No. 25)
The minimum value of y in the equation y = x\(^2\) - 6x + 8 is
8
3
7
-1
Uitleg
y = x\(^2\) - 6x + 8
\(\frac{dy}{dx}\) = 2x - 6
\(\frac{dy}{dx}\) = 0
2x - 6 = 0
x = 3
\(\therefore\) y = 3\(^2\) - 6(3) + 8
= 9 - 18 + 8
= -1