At what value of x is the function x2 x 1 minim... - JAMB Mathematics 1990 Question
At what value of x is the function x2 + x + 1 minimum?
A
1
B
\(\frac{3}{4}\)
C
\(\frac{5}{3}\)
D
9
correct option: a
x + x + 1
\(\frac{dy}{dx}\) = 2x + 1
At the turning point, \(\frac{dy}{dx}\) = 0
2x + 1 = 0
x = -\(\frac{1}{2}\)
\(\frac{d^2y}{dx^2}\) = 2 > 0(min Pt)
= \(\frac{1}{4}\) + \(\frac{1}{2}\)
= 1
\(\frac{dy}{dx}\) = 2x + 1
At the turning point, \(\frac{dy}{dx}\) = 0
2x + 1 = 0
x = -\(\frac{1}{2}\)
\(\frac{d^2y}{dx^2}\) = 2 > 0(min Pt)
= \(\frac{1}{4}\) + \(\frac{1}{2}\)
= 1
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