JAMB - Mathematics (1987 - No. 15)
If a = u\(^2\) - 3v\(^2\) and b = 2uv + v\(^2\) evaluate (2a - b)(a - b\(^2\)), when u = 1 and v = -1
9
15
27
33
คำอธิบาย
a = u\(^2\) - 3v\(^2\) = (1)2 - 3(-1) = -2
b = b = 2uv + v\(^2\)
= 2(1)(-1) + (-1)2 = -1
∴ 2(2a - b)(a - b\(^2\)) = [2(-2) + 1](-2 - (-1)\(^2\))
= (-3)( - 3)
= 9
b = b = 2uv + v\(^2\)
= 2(1)(-1) + (-1)2 = -1
∴ 2(2a - b)(a - b\(^2\)) = [2(-2) + 1](-2 - (-1)\(^2\))
= (-3)( - 3)
= 9