# 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 = 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.

(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.

(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.

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