NCERT Solutions Class 8th Maths Chapter – 2 Linear Equations in One Variable Exercise 2.6

NCERT Solutions Class 8th Maths Chapter – 2 Linear Equations in One Variable

TextbookNCERT
Class 8th
Subject Mathematics
Chapter2nd
Chapter Name Linear Equations in One Variable
CategoryClass 8th Maths
Medium English
SourceLast Doubt

NCERT Solutions Class 8th Maths Chapter 2 Linear Equations in One Variable

Chapter – 2

Linear Equations in One Variable

Exercise 2.6

Solve the following equations.

1. (8x – 3)/3x = 2

Solution:
(8x – 3)/3x = 2
⇒ 8x/3x – 3/3x = 2
⇒ 8/3 – 1/x = 2
⇒ 8/3 – 2 = 1/x
⇒ (8 – 6)/3 = 1/x
⇒ 2/3 = 1/x
⇒ x = 3/2

2. 9x/(7 – 6x) = 15

Solution:
9x/(7 – 6x) = 15
⇒ 9x = 15(7 – 6x)
⇒ 9x = 105 – 90x
⇒ 9x + 90x = 105
⇒ 99x = 105
⇒ x = 105/99 = 35/33

3. z/(z + 15) = 4/9

Solution:
z/(z + 15) = 4/9
⇒ z = 4/9 (z + 15)
⇒ 9z = 4(z + 15)
⇒ 9z = 4z + 60
⇒ 9z – 4z = 60
⇒ 5z = 60
⇒ z = 12

4. (3y + 4)/(2 – 6y) = -2/5

Solution:
(3y + 4)/(2 – 6y) = -2/5
⇒ 3y + 4 = -2/5 (2 – 6y)
⇒ 5(3y + 4) = -2(2 – 6y)
⇒ 15y + 20 = -4 + 12y
⇒ 15y – 12y = -4 – 20
⇒ 3y = -24
⇒ y = -8

5. (7y + 4)/(y + 2) = -4/3

Solution:
(7y + 4)/(y + 2) = -4/3
⇒ 7y + 4 = -4/3 (y + 2)
⇒ 3(7y + 4) = -4(y + 2)
⇒ 21y + 12 = – 4y – 8
⇒ 21y + 4y = -8 – 12
⇒ 25y = -20
⇒ y = -20/25 = -4/5

6. The ages of Hari and Harry are in the ratio 5:7. Four years from now the ratio of their ages will be 3:4. Find their present ages.

Solution:
Let the age of Hari be 5x and Harry be 7x. 4 years later,
Age of Hari = 5x + 4 Age of Harry = 7x + 4
According to the question,
(5x + 4)/(7x + 4) = ¾
⇒ 4(5x + 4) = 3(7x + 4)
⇒ 20x + 16 = 21x + 12
⇒ 21x – 20x = 16 – 12
⇒ x = 4
Hari age = 5x = 5 × 4 = 20 years
Harry age = 7x = 7 × 4 = 28 years

7. The denominator of a rational number is greater than its numerator by 8. If the numerator is increased by 17 and the denominator is decreased by 1, the number obtained is 3/2. Find the rational number.

Solution:
Let the numerator be x then denominator will be (x + 8)
According to the question,
(x + 17)/(x + 8 – 1) = 3/2
⇒ (x + 17)/(x + 7) = 3/2
⇒ 2(x + 17) = 3(x + 7)
⇒ 2x + 34 = 3x + 21
⇒ 34 – 21 = 3x – 2x
⇒ 13 = x
The rational number is x/(x + 8) = 13/21

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