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Exercise 3.2 (Addition and Subtraction of Algebraic expressions)

7th Maths : Term 1 Unit 3 : Algebra : Addition and Subtraction of Algebraic expressions : Exercise 3.2 : Fill in the blanks, Say true or false, Find the value of the following, Objective type questions, Text Book Back Exercises Questions with Answers, Solution

Exercise 3.2

1. Fill in the blanks.

(i) The addition of −7b and 2b is –7b + 2b = –5b.

(ii) The subtraction of 5m from −3m is –3m – 5m = –8m

(iii) The additive inverse of − 37xyz is 37 xyz

2. Say True or False.

(i) The expressions 8x + 3y and 7x + 2y can not be added. (False)

(ii) If x is a natural number, then x + 1 is its predecessor. (False)

(iii) Sum of a − b + c and −a + b − c is zero. (True)

3. Add: (i) 8x, 3x, (ii) 7mn, 5mn (iii) −9y, 11y, 2y

(i) 8x, 3x

8x + 3x = 11 x

(ii) 7mn, 5mn

7mn + 5mn =12 mn

(iii) –9y, l l y, 2y

–9y + 11y + 2y

–9y + 13y = 4y

4. Subtract:

(i) 4k from 12k (ii) 15q from 25q (iii) 7xyz from 17xyz.

i) 4k from 12k = 12k – 4k = 8k

ii) 15q from 25q = 25q – 15q = 10q

iii) 7xyz from 17xyz = 17xyz – 7xyz = 10xyz

5. Find the sum of the following expressions

(i) 7p + 6q, 5pq, q + 16p

(ii) a + 5b + 7c, 2a + 10b + 9c

(iii) mn + t, 2mn − 2t, − 3t + 3mn

(iv) u + v, u v, 2u + 5v, 2u − 5v.

(v) 5xyz − 3xy, 3zxy − 5yx

(i) 7p + 6q, 5p – q, q + 16p

7p + 6q + 5p – q + q + 16p

7p + 5p + 16p + 6qq + q

(7 + 5 + I6)p + (6 – 1 + l)q

28p + 6q

(ii) a + 5b + 7c, 2a + 106 + 9c

a + 5b + 7c + 2a + 10b + 9c

a4 – 2a + 5b + 10b + 7c + 9c

(1+2) a + (5 + 10) b + (7 + 9) c

3a + 15b + 16c

(iii) mn + t, 2mn – 2t, – 3t + 3mn

mn + t + 2mn – 2t – 3t + 3mn

mn + 2mn + 3mn + t – 2t – 3t

(1 + 2 + 3) mn + (1 – 2 – 3) t

6mn – 4t

(iv) u + v, u – v, 2u + 5v, 2u – 5v.

u + v + u – v + 2u + 5v + 2u – 5v

(1 + 1 + 2 + 2)u + (1 – 1 + 5 – 5)v

6u + Ov

6u

(v) 5xyz – 3xy, 3zxy – 5yx

5xyz – 3xy + 3zxy – 5yx

(5+3) xyz + (–3–5).xy

8 xyz – 8 xy

6. Subtract

(i) 13x + 12y − 5 from 27x + 5y − 43

(ii) 3p + 5 from p − 2q + 7

(iii) m + n from 3m − 7n.

(iv) 2y + z from 6z − 5y.

(i) 13x + 12y – 5 from 27x + 5y – 43

27x + 5y– 43 – (13x + 12y – 5)

27x + 5y – 43 –13x –12y + 5

(27 –13) x + (5 – 12) y+ (–43 +5)

14x –7y – 38

(ii) 3p + 5 from p – 2q + 7

p – 2q + 7 – (3p + 5)

p – 2q + 7 – 3p – 5

(l–3) p + (–2q) + (7 – 5)

–2p – 2q + 2

(iii) m + n from 3m – 7n.

3m – 7n – (m + n)

3m – 7n – m – n

(3 – l)m + (–7 –1)n

2m – 8n

(iv) 2y + z from 6z – 5y.

6z – 5y – (2y + z)

6z – 5y – 2y – z

(–5 –2) y + (6 – 1) z

–7y + 5z

7. Simplify

(i) (x + yz) + (3x − 5y + 7z) − (14x + 7y − 6z)

(ii) p + p + 2 + p + 3 − p − 4 − p − 5 + p + 10

(iii) n + (m + 1) + (n + 2) + (m + 3) + (n + 4) + (m + 5)

(i) (x +y– z) + (3x – 5y+ 7z) – (14x + 7y– 6z)

x+y – z + 3x – 5y + 7z – 14x – 7y + 6z

x + 3x – 14x + y – 5y – 7y – z + 7z + 6z

(1 + 3 – 14) x + (1 – 5 – 7) y + (–1 +7 +6)z

–10x – 11y + 12z

(ii) p + p +2 + p + 3 – p – 4 – p 5 + p + 10

p + p + p + p – p – p + 2 + 3 – 4 – 5 + 10

(1 + 1 + 1 + 1 – 1 – l)p + 2 + 3 + 10 – 4 – 5

(4 – 2)p + 15 – 9

2p + 6

(iii) n + (m + 1) + (n + 2) + (m + 3) + (n + 4) + (m + 5)

n + m + l + n + 2 + m + 3 + n + 4 + m + 5

m + m + m + n + n + n + 1 + 2 + 3 + 4 + 5

(1 + 1 + l)m + (1 + 1 + l)n + 15

3m + 3n + 15

Objective type questions

8. The addition of 3mn, −5mn, 8mn and −4mn is

(i) mn

(ii) −mn

(iii) 2mn

(iv) 3mn

9. When we subtract ‘a’ from ‘– a’, we get _______

(i) 0

(ii) 2a

(iii) −2a

(iv) –a

10. In an expression, we can add or subtract only…

(i) Like terms

(ii) Unlike terms

(iii) All terms

(iv) None of the above

EXERCISE-3.2

1. (i) –5b (ii) –8m (iii) 37xyz

2. (i) False (ii) False (iii) True

3. (i) 11x (ii) 12mn (iii) 4y

4. (i) 8k (ii) 10q (iii) 10xyz

5. (i) 28 p + 6q (ii) 3a + 15b + 16c (iii) 6 mn − 4t (iv) 6u (v) 8 xyz − 8xy

6. (i) 14x − 7y − 38 (ii) −2 p − 2q + 2 (iii) 2 m − 8n (iv) −7 + 5

7. (i) −10 x − 11y + 12z (ii) 2p + 6 (iii) 3m + 3n + 15

Objective type questions

8. (iii) 2mn

9. (iii) −2a

10. (i) Like terms

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7th Maths : Term 1 Unit 3 : Algebra : Exercise 3.2 (Addition and Subtraction of Algebraic expressions) | Questions with Answers, Solution | Algebra | Term 1 Chapter 3 | 7th Maths