Exercise : 9


1. Four of the five parts numbered (a), (b), (c), (d) and (e) are exactly equal. Which of the parts is not equal to the other four? The number of that part is the answer.
(a) (2x + 3y)2
(b) (2y – x)2 + y(16x + 5y)
(c) 4x(x + 2y) + y(4x + 9y)
(d) (2x + 2y)2 + y(4x + 5y)
(e) (2x – y)2 + 8y(2x + y)
Ans.b

Others are requal to 4x2 + 9y2 + 12xy.

2. Four of the five parts numbered (a), (b), (c), (d) and (e) in the following equation are exactly equal. Which part is not equal to the other four ? The number of that part is the answer.
(a) (x + 2y)(3x + 2y)
(b) (x + 2y)2 + 2x(x + 2y)
(c) (3x + 2y)2 – 2x(3x + 2y)
(d) 3x(x + 2y) + 2y(x + 2y)
(e) x(3x + 2y) – 2y(3x – 2y)
Ans.e

Others are equal to 3x2 + 8xy + 4y2

3. Four of the five parts numbered (a), (b), (c), (d) and (e) are exactly equal. Which of the parts is not equal to the other four? The number of that part is the answer.
(a) (a + b)(a – 2b)
(b) a2 – b(a + 2b)
(c) a2 + b2 – ab – 3b2
(d) (a + b)(a – b) + ab
(e) (a – b)2 + b(a – 3b)
Ans.d

Others equal a2 – ab – 2b2 whereas (d) equals a2 + ab – b2 .

4. Four of the five parts numbered (a), (b), (c), (d) and (e) in the following equation are exactly equal. Which part is not equal to the other four? The number of that part is the answer.
(a) x(x + y)2 – 2x2y
(b) x(x + y)2 + 2x2y
(c) x(x2 – y2)
(d) x[(x + y)2 – 2xy]

(e) x[(x + y)2 – 2xy2]

Ans.e

Others are x3 + xy2

5. Which of the following has fractions in ascending order?
(a) 25, 35, 13, 47, 56, 67
(b) 13, 25, 35, 56, 47, 67
(c) 13, 25, 35, 47, 56, 67
(d) 13, 25, 47, 35, 56, 67
(e) None of these
Ans.d

13 = 0.33; 25 = 0.4; 47 = 0.57; 35 = 0.6; 56 = 0.83 and 67 = 0.85