**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.