NCERT Solutions For Class 6 Maths Algebra Exercise 11.5

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NCERT Solutions For Class 6 Maths Algebra Exercise 11.5

NCERT Solutions For Class 6 Maths Chapter 11 Algebra Ex 11.5

Exercise 11.5

Ex 11.5 Class 6 Maths Question 1.
State which of the following are equations (with a variable). Give reason for your answer. Identify the variable from the equations with a variable.
(a) 17 = x + 7
(b) (t – 7) > 5
(c) \frac { 4 }{ 2 }= 2
(d) (7 x 3) – 19 = 8
(e) 5 x 4 – 8 = 2x
(f) x -2 = 0
(g) 2m < 30
(h) 2n + 1 = 11
(i) 7 = (11 x 5) – (12 x 4)
(j) 7 = (11 x 2) + p
(k) 20 = 5y
(l) \frac { 3q }{ 2 }< 5 (m) z + 12 > 24
(n) 20 – (10 – 5) = 3 x 5
(o) 7 – x = 5
Solution:
(a) 17 = x + 7 is an equation with a variable x.
(b) (t – 7) > 5 is not an equation because it does not have ‘=’ sign.
(c) \frac { 4 }{ 2 }= 2 is not an equation because it has no variable.
(d) (7 x 3) – 19 = 8 is not an equation because it has no variable.
(e) 5 x 4 – 8 = 2x is an equation with a variable x.
(f) x – 2 = 0 is an equation with a variable x.
(g) 2m < 30 is not an equation because it does not have ‘=’ sign.
(h) 2n + 1 = 11 is an equation with a variable n.
(i) 7 = (11 x 5) – (12 x 4) is not an equation because it does not have a variable.
(j) 7 = (11 x 2) + p is an equation with a variable p.
(k) 20 = 5y is an equation with a variable y.
(l) \frac { 3q }{ 2 }< 5 is not an equation because it does not have ‘=’ sign. (m) z + 12 > 24 is not an equation because it does not have ‘=’ sign.
(n) 20 – (10 – 5) = 3 x 5 is not an equation because it has no variable.
(o) 7 – x = 5 is an equation with a variable x.

Ex 11.5 Class 6 Maths Question 2.
Complete the entries in the third column of the table.

S. No. Equation Value of variable Equations satisfied Yes /No
(a) 10y = 80 y = 10
(b) 10y = 80 y = 8
(c) 10y = 80 y = 5
(d) 4l = 20 l = 20
(e) 4l = 20 l = 80
(f) 4l = 20 l = 5
(g) b + 5 = 9 b = 5
(h) b + 5 = 9 b = 9
(i) b + 5 = 9 b = 4
(J) h – 8 = 5 h = 13
(k) h – 8 = 5 h = 8
(l) h – 8 = 5 h = 0
(m) P + 3 = 1 p = 3
(n) p + 3 = 1 p = 1
(o) p + 3 = 1 p = 0
(P) p + 3 = 1 p = -1
(q) p + 3 = 1 p = -2

Solution:

S. No. Equation Value of variable Equations satisfied Yes /No
(a) 10y = 80 y = 10 No
(b) 10y = 80 y = 8 Yes
(c) 10y = 80 y = 5 No
(d) 4l = 20 l = 20 No
(e) 4l = 20 l = 80 No
(f) 4l = 20 l = 5 Yes
(g) b + 5 = 9 b = 5 No
(h) b + 5 = 9 b = 9 No
(i) b + 5 = 9 b = 4 Yes
(J) h – 8 = 5 h = 13 Yes
(k) h – 8 = 5 h = 8 No
(l) h – 8 = 5 h = 0 No
(m) P + 3 = 1 p = 3 No
(n) p + 3 = 1 p = 1 No
(o) p + 3 = 1 p = 0 No
(P) p + 3 = 1 p = -1 No
(q) p + 3 = 1 p = -2 Yes

Ex 11.5 Class 6 Maths Question 3.
Pick out the solution from the values given in the brackets next to each equation. Show that the other values do not satisfy the equation.
(а) 5m = 60 (10, 5, 12, 15)
(b) n + 12 = 20 (12, 8, 20, 0)
(c) p – 5 = 5 (0, 10, 5, -5)
(d) \frac { q }{ 2 }= 7 (7, 2, 10, 14)
(e) r – 4 = 0 (4, -4, 8, 0)
(f) x + 4 = 2 (-2, 0, 2, 4)
Solution:
(a) For m = 10, LHS = 5 x 10 = 50, RHS = 60
Here, LHS ≠ RHS
∴ m = 10 is not the solution of the equation
For m = 5, LHS = 5×5 = 25, RHS = 60
Here, LHS ≠ RHS
∴ m = 5 is not the solution of the equation
For m = 12, LHS = 5 x 12 = 60, RHS = 60
Here, LHS = RHS
∴ m = 12 is the solution of the equation
For m = 15 LHS = 5 x 15 = 75, RHS = 60
Here, LHS ≠ RHS
∴ m = 15 is not the solution of the equation

(b) n + 12 = 20 (12, 8, 20, 0)
For n = 12, LHS = 12 + 12 = 24, RHS = 20
Here, LHS ≠ RHS
∴ n = 12 is not the solution of the equation
For n = 8, LHS = 8 + 12 = 20, RHS = 20
Here, LHS = RHS
∴ n = 8 is the solution of the equation
For n = 20, LHS = 20 + 12 = 32, RHS = 20
Here, LHS ≠ RHS
∴ n = 20 is not the solution of the equation
For n = 0, LHS = 0 + 12 – 12, RHS = 20
Here, LHS ≠ RHS
∴ n= 0 is not the solution of the equation

(c) p – 5 = 5 (0, 10, 5, -5)
For p = 0, LHS = 0 – 5 = -5, RHS = 5
Here, LHS ≠ RHS
∴ p = 0 is not the solution of the equation
For p = 10, LHS = 10 – 5 = 5, RHS = 5
Here, LHS = RHS
∴ p = 10 is the solution of the equation
For p = 5, LHS = 5-5-0, RHS = 5
Here LHS ≠ RHS
∴ p = 5 is not the solution of the equation
For p = 5, LHS = 5 – 5 = 0, RHS = 5
Here, LHS ≠ RHS
∴ p = -5 is not the solution of the equation

(d) \frac { q }{ 2 }= 7 (7, 2, 10, 14)
For q = 7, LHS = \frac { 7 }{ 2 }, RHS = 7
Here LHS ≠ RHS
∴ q = 7 is not the solution of the equation
For q = 2, LHS = \frac { 2 }{ 2 }= 1, RHS = 7
Here, LHS ≠ RHS
∴ q = 2 is not the solution of the equation
For q = 10, LHS = \frac { 10 }{ 2 }= 5, RHS = 7
Here, LHS ≠ RHS
For q = 14, LHS = \frac { 14 }{ 2 }= 7, RHS = 7
Here, LHS = RHS
∴ q = 14 is the solution of the equation

(e) r – 4 = 0 (4, -4, 8, 0)
For r = 4, LHS = 4 – 4 = 0, RHS = 0
Here, LHS = RHS
∴ r = 4 is the solution of the equation
For r = -4, LHS = -4 – 4 = -8, RHS = 0
Here, LHS ≠ RHS
∴ r = -4 is not the solution of the equation
For r = 8, LHS = 8 – 4 = 4, RHS = 0
Here, LHS ≠ RHS
For r = 8 is not the solution of the equation
For r = 0, LHS = 0 – 4 = – 4, RHS = 0
Here, LHS ≠ RHS
∴ r = 0 is not the solution of the equation

(f) x + 4 = 2 (-2, 0, 2, 4)
For x = -2, LHS = -2 + 4 = 2, RHS = 2
Here, LHS – RHS
∴ x = -2 is the solution of the equation
For x = 0, LHS = 0 + 4 – 4, RHS = 2
Here, LHS ≠ RHS
∴ x = 0 is not the solution of the equation
For x = – 2, LHS = -2 + 4 – 6, RHS = 2
Here, LHS ≠ RHS
∴ x = 2 is not the solution of the equation
For r = 4, LHS = 4 + 4 = 8, RHS = 2
Here, LHS ≠ RHS
∴ x = 4 is not the solution of the equation

Ex 11.5 Class 6 Maths Question 4.
(a) Complete the table and by inspection of the table find the solution to the equation m + 10 = 6
NCERT Solutions For Class 6 Maths Chapter 11 Algebra
(b) Complete the table and by inspection of the table find the solution to the equation 51 – 35
NCERT Solutions For Class 6 Maths Chapter 11 Algebra

(c) Complete the table and find the solution of the equation g = 4 using the table.
NCERT Solutions For Class 6 Maths Chapter 11 Algebra
(d) Complete the table and find the solution to the equation m – 7 = 3
NCERT Solutions For Class 6 Maths Chapter 11 Algebra
Solution:
(a) By inspections, we have
NCERT Solutions For Class 6 Maths Chapter 11 Algebra
So, m – 6 is the solution of the equation.

(b) Given that 5t = 35
NCERT Solutions For Class 6 Maths Chapter 11 Algebra
So, t = 7 is the solution of the equation.

(c) Given that \frac { z }{ 3 }= 35
NCERT Solutions For Class 6 Maths Chapter 11 Algebra
So, z = 12 is the solution of the equation.

(d) Given that m – 7 = 3
NCERT Solutions For Class 6 Maths Chapter 11 Algebra
So, m = 10 is the solution of the equation.

Ex 11.5 Class 6 Maths Question 5.
Solve the following riddles, you may yourself construct such riddles. Who am I?
(i) Go round a square
Counting every corner
Thrice and no more!
Add the count to me
To get exactly thirty four!
NCERT Solutions For Class 6 Maths Chapter 11 Algebra

(ii) For each day of the week
Make an upcount from me
If you make no mistake
you will get twenty three!
NCERT Solutions For Class 6 Maths Chapter 11 Algebra

(iii) I am a special number
Take away from me a six!
A whole cricket team
You will still be able to fix!

(iv) Tell me who I am
I shall give you a pretty clue!
you will get me back
If you take me out of twenty two!
Solution:
(i) According to the condition,
I + 12 = 34 or x + 12 = 34
∴ By inspection, we have
22 + 12 = 34
So, I am 22.

(ii) Let I am ‘x’.
We know that there are 7 days in a week.
∴ upcounting from x for 7, the sum = 23
By inspections, we have
16 + 7 = 23
∴ x = 16
Thus I am 16.

(iii) Let the special number be x and there are 11 players in cricket team.
∴ Special Number -6 = 11
∴ x – 6 = 11
By inspection, we get
17 – 6 = 11
∴ x = 17
Thus I am 17.

(iv) Suppose I am ‘x’.
∴ 22 – I = I
or 22 – x = x
By inspection, we have
22 – 11 = 11
∴ x = 11
Thus I am 11.

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