
Difficult Problems in mathematics From post utme (ABU 2008)
Mathematics
Chima Sunday (Tutor)
17052016 12:54:00 +0000Hey friends! Checkout this mathematics questions, about 70% of students that attempted it got it wrong. Try it and see if you can get it right
1. X*Y = XY  Y^{2}; Evaluate (2x + y)*(y + 2x)
A. 4xy
B. 4x^{2}
C. 0
D. 1Updated Solution
X*Y = XY  Y^{2}
here X = (2x + y), and Y = (y + 2x) = (2x + y)
thus X*Y = (2x + y)(2x + y)  (2x + y)^{2}
= (2x + y)^{2}  (2x + y)^{2}
= 0, so answer is Option C2. Evaluate x^{2} + 1/x^{2} if x  1/x = 5
A. 24
B. 25
C. 26
D. 27Updated Solution
x^{2} + 1/x^{2} = ?
but x  1/x = 5
now sqauring both side
(x  1/x)^{2} = 5^{2}
(x  1/x)(x  1/x) = 25
x^{2} + 1/x^{2}  2 = 25
x^{2} + 1/x^{2} = 25 + 2 = 27
So answer is Option D3. If (2x  1)(2x + 3) + (2x + 1) = ax^{2} + bx + c; Find a,b,c
A. 0,6,6
B. 8,0,0
C. 8,0,6
D. 4,6,2Updated Solution
(2x  1)(2x + 3) + (2x + 1) = a^{2} + bx + c
opening the bracket
4x^{2} + 6x  2  3 + 2x + 1 = ax^{2} + bx + c 4x^{2} + 6x  2 = ax^{2} + bx + c
so by comparison
a = 4
b = 6
c = 2
so answer is Option D

Chima Sunday (Tutor)
Solutions to the questions above. Keep the fire burning.
0 14062016 13:17:00 +0000

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