Algebra
Exercise 11.3
EX 11.3 QUESTION 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.
Solution:
Given numbers = 5, 7 and 8
- 8 + (5 + 7)
- 5 + (8 – 7)
- 8 + (5 x 7)
- 7 – (8 – 5)
- 7 x (8 + 5)
- 5 x (8 + 7)
- 8 x (5 + 7)
- 7 + (8 – 5)
- (5 x 7) – 8
- 7 + (8 x 5)
EX 11.3 QUESTION 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
Solution:
(c) and (d) .
EX 11.3 QUESTION 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, 2y – 17
(d) 7m, -7m + 3, -7m – 3
Solution:
(a) z + 1 = Addition
z – 1 = Subtraction
y + 17 = Addition
y – 17 = Subtraction
(b) 17y = Multiplication
y / 17 = Division
5z = Multiplication
(c) 2y + 17 = Multiplication, and addition
2y – 17 = Multiplication and subtraction
(d) 7m = multiplication
-7m + 3 = Multiplication, and addition
-7m – 3 = Multiplication and subtraction
EX 11.3 QUESTION 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
Solution:
(a) p + 7
(b) p – 7
(c) 7p
(d) p / 7
(e) -m – 7
(f) -5p
(g) –p / 5
(h)-5p
EX 11.3 QUESTION 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.
Solution:
(a) 2m + 11
(b) 2m – 11
(c) 5y + 3
(d) 5y – 3
(e) -8y
(f) -8y + 5
(g) 16 – 5y
(h) -5y + 16
EX 11.3 QUESTION 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.
Solution:
(a)
- (t + 4),
- (t – 4),
- 4t,
- (t / 4),
- (4 / t),
- (4 – t),
- (4 + t)
(b)
- 2y + 7,
- 2y – 7,
- 7y + 2
- 7y – 2
- 7y / 2
- 2y / 7…. and so on.