NCERT Solution For Class 6, Maths, Chapter 11, Algebra, Exercise 11.3
Exercise 11.3
Q.1. Make up as many expressions with numbers (no variables) as you can from three numbers 5, 7 and 8. Every number should be used not more than once. Use only Addition, Subtraction and Multiplication.
Ans: Some of the expressions formed by 5, 7 and 8 are as follows:
(5 x 7) + 8
(5 x 7) – 8
(5 + 7) – 8
5 + (8 – 7)
(8 + 5) – 7
(8 + 7) – 5
5 + (8 x 7)
5 – (7 + 8)
5 – (7 x 8)
Q.2. Which out of the following are expressions with numbers only?
(a) y + 3
(b) (7 × 20) – 8z
(c) 5 (21 – 7) + 7 × 2
(d) 5
(e) 3x
(f) 5 – 5n
(g) (7 × 20) – (5 × 10) – 45 + p
Ans: (c) and (d) are the expressions with numbers only.
Q.3. Identify the operations (addition, subtraction, division, multiplication) in forming the following expressions and tell how the expressions have been formed.
(a) z +1, z – 1, y + 17, y – 17
(b) 17y, y/17 , 5z
(c) 2y + 17, 2 y – 17
(d) 7 m, – 7 m + 3, – 7 m – 3
Ans: (a) z +1, z – 1, y + 17, y – 17
z + 1 = 1 is added to z (Addition)
z – 1 = 1 is subtracted from z ( Subtraction)
y + 17 = 17 is added to y (Addition)
y – 17 = 17 is subtracted from y (Subtraction)
(b) 17y, y/17 , 5z
17y = y is multiplied by 17 (Multiplication)
y / 17 = y is divided by 17 (Division)
5z = z is multiplied by 5 (Multiplication)
(c) 2y + 17, 2 y – 17
2y + 17 = y is multiplied by 2 and 17 is added to the result (Multiplication and addition)
2y – 17 = y is multiplied by 2 and 17 is subtracted to the result (Multiplication and subtraction)
(d) 7 m, – 7 m + 3, – 7 m – 3
7m = m is multiplied by 7 (Multiplication)
-7m + 3 = m is multiplied by -7 and 3 is added to the result (Multiplication and addition)
-7m – 3 = m is multiplied by -7 and 3 is subtracted to the result (Multiplication and subtraction)
Q.4. Give expressions for the following cases.
(a) 7 added to p (b) 7 subtracted from p
(c) p multiplied by 7 (d) p divided by 7
(e) 7 subtracted from – m (f) – p multiplied by 5
(g) – p divided by 5 (h) p multiplied by – 5
Ans: (a) 7 added to p = p + 7
(b) 7 subtracted from p = p – 7
(c) p multiplied by 7 = 7p
(d) p divided by 7 = p/7
(e) 7 subtracted from – m = -m – 7
(f) – p multiplied by 5 = -p x 5 = -5p
(g) – p divided by 5 = -p/5
(h) p multiplied by – 5 = p x -5 = -5p
Q.5. Give expressions in the following cases.
(a) 11 added to 2m
(b) 11 subtracted from 2m
(c) 5 times y to which 3 is added
(d) 5 times y from which 3 is subtracted
(e) y is multiplied by – 8
(f) y is multiplied by – 8 and then 5 is added to the result
(g) y is multiplied by 5 and the result is subtracted from 16
(h) y is multiplied by – 5 and the result is added to 16.
Ans: (a) 11 added to 2m = (2m + 11)
(b) 11 subtracted from 2m = (2m – 11)
(c) 5 times y to which 3 is added = (5y + 3)
(d) 5 times y from which 3 is subtracted = (5y – 3)
(e) y is multiplied by -8 = – 8y
(f) y is multiplied by -8 and then 5 is added to the result = (-8y + 5)
(g) y is multiplied by 5 and the result is subtracted from 16 = (16 – 5y)
(h) y is multiplied by -5 and the result is added to 16 = (-5y + 16)
Q.6. (a) Form expressions using t and 4. Use not more than one number operation. Every expression must have t in it.
(b) Form expressions using y, 2 and 7. Every expression must have y in it. Use only two number operations. These should be different.
Ans: (a)(t + 4), (t – 4), 4t, (t / 4), (4 / t), (4 – t), (4 + t) are the expressions using t and 4.
(b) 2y + 7, 2y -7, 7y + 2, 7y – 2 and so on.