JAMB - Mathematics (2014 - No. 31)
Find the minimum value of y = x2 - 2x - 3
4
1
-1
-4
Vysvětlení
y = x2 - 2x - 3,
Then \(\frac{\delta y}{\delta x} = 2x - 2\)
But at minimum point,\(\frac{\delta y}{\delta x} = 0\),
Which means 2x - 2 = 0
2x = 2
x = 1.
Hence the minimum value of y = x2 - 2x - 3 is;
ymin = (1)2 - 2(1) - 3
ymin = 1 - 2 - 3
ymin = -4
Then \(\frac{\delta y}{\delta x} = 2x - 2\)
But at minimum point,\(\frac{\delta y}{\delta x} = 0\),
Which means 2x - 2 = 0
2x = 2
x = 1.
Hence the minimum value of y = x2 - 2x - 3 is;
ymin = (1)2 - 2(1) - 3
ymin = 1 - 2 - 3
ymin = -4