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## Tamilnadu Samacheer Kalvi 7th Maths Solutions Term 1 Chapter 3 Algebra Ex 3.1

Question 1.

Fill in the blanks

(i) The variable in the expression 16x – 7 is _____

(ii) The constant term of the expression 2y – 6 is _____

(iii) In the expression 25m + 14M, the type of the terms are ______ terms

(iv) The number of terms in the expression 3ab + 4c – 9 is _____

Hint: Terms are 3ab, 4c – 9.

(v) The numerical co-efficient of the term -xy is ______

Hint: -x,y = (- 1 )xy.

Solution:

(i) x

(ii) -6

(iii) unlike

(iv) three

(v) -1

Question 2.

Say true or False

(i) x + (-x) = 0.

(ii) The co-efficient of ab in the term 15 abc is 15.

Hint: Coefficient of ab is 15c

(iii) 2pq and – 7qp are like terms.

(iv) When y = -1, the value of the expression 2y – 1 is 3.

Hint: 2(-1) – 1 = -2 – 1 = – 3

Solution:

(i) True

(ii) False

(iii) True

(iv) False

Question 3.

Fing the numerical co-efficient of each of the following terms: -3yx, 12k, y, 121bc, -x, 9pq, 2ab.

Solution:

(i) Numerical co-efficient of-3yx is – 3

(ii) Numerical co-efficient of 12k is 12

(iii) Numerical coefficient of y is 1

(iv) Numerical co-efficient of 1216c is 121

(v) Numerical co-efficient of – x is – 1

(vi) Numerical co-efficient of 9pq is 9

(vii) Numerical co-efficient of 2ab is 2

Question 4.

Write the variables, constants and terms of the following expressions,

(i) 18 + x – y

(ii) 7p – 4q + 5

(iii) 29x + 13y

(iv) b + 2

Solution:

Question 5.

Identify the like terms among the following 7x, 5y, -8x, 12y, 6z, z, -12x, -9y, 11 z

Solution:

Question 6.

If x = 2 andy = 3, then find the value of the following expressions,

(i) 2x – 3y

(ii) x + y

(iii) 4y – x

(iv) x + 1 – y

Solution:

Given x = 2; y = 3.

(i) 2x – 3y = 2 (2) – 3 (3) = 4 – 9

= 4 + (Additive inverse of 9)

= 4 +(-9) = -5

(ii) x + y = 2 + 3 = 5

(iii) 4y – x = 4 (3) – 2 = 12 – 2 = 10

(iv) x + 1 – y = 2 + 1 – 3 = 3 – 3 = 0

Objective Type Questions

Question 1.

An algebraic statement which is equivalent to the verbal statement “Three times the sum of ‘x’ and ‘y’ is

(i) 3 (x + y)

(ii) 3 + x + y

(iii) 3x + y

(iv) 3 + xy

Solution:

(i) 3 [(x + y)]

Question 2.

The numerical co-efficient of -7mn is

(i) 7

(ii) -7

(iii) p

(iv) -p

Solution:

(ii) -7

Question 3.

Choose the pair of like terms

(i) 7p, 7x

(ii) 7r, 7x

(iii) – 4x, 4

(iv) – 4x, 7x

Solution:

(iv) -4x, 7x

Question 4.

The value of 7a – 4b when a = 3, b = 2 is

(i) 21

(ii) 13

(iii) 8

(iv) 32

Solution:

(ii) 13

Hint: 7(3) – 4(2) = 21 – 8 = 13