JAMB - Mathematics (1979 - No. 38)

If y = x\(^2\) - 2x - 3, find the least value of y and the corresponding value of x

x = 3, y = 3

x = 1, y = -3

x = 4, y = 1

x = 1, y = -4

x = 2, y = -3

If the graph of eqn. y = x\(^2\) - 2x - 3 is plot and drawn, the lease value of y = -4 while the corresponding value of x = 1

x = 1, y = -4

\(\frac{dy}{dx}\) = 0 = 2x - 2

2x = 2

x = 1

put x = 1 in y = 2x\(^2\) - 2x - 3

y = - 4

x= 1, y = -4