class 8 chapter 2 exercise 2.3

class 8 chapter 2 exercise 2.3

Question 1:

Solve and check result: 3x = 2x + 18

Answer:

3x = 2x + 18

On transposing 2x to L.H.S, we obtain

3x − 2x = 18

x = 18

L.H.S = 3x = 3 × 18 = 54

R.H.S = 2x + 18 = 2 × 18 + 18 = 36 + 18 = 54

L.H.S. = R.H.S.

Hence, the result obtained above is correct.


Question 2:

Solve and check result: 5t − 3 = 3t − 5

Answer:

5t − 3 = 3t − 5

On transposing 3t to L.H.S and −3 to R.H.S, we obtain

5t − 3t = −5 − (−3)

2t = −2

On dividing both sides by 2, we obtain

t = −1

L.H.S = 5t − 3 = 5 × (−1) − 3 = −8

R.H.S = 3t − 5 = 3 × (−1) − 5 = − 3 − 5 = −8

L.H.S. = R.H.S.

Hence, the result obtained above is correct.



Question 3:

Solve and check result: 5x + 9 = 5 + 3x

Answer:

5x + 9 = 5 + 3x

On transposing 3x to L.H.S and 9 to R.H.S, we obtain

5x − 3x = 5 − 9

2x = −4

On dividing both sides by 2, we obtain

x = −2

L.H.S = 5x + 9 = 5 × (−2) + 9 = −10 + 9 = −1

R.H.S = 5 + 3x = 5 + 3 × (−2) = 5 − 6 = −1

L.H.S. = R.H.S.

Hence, the result obtained above is correct.




Question 4:

Solve and check result: 4z + 3 = 6 + 2z

Answer:

4z + 3 = 6 + 2z

On transposing 2z to L.H.S and 3 to R.H.S, we obtain

4z − 2z = 6 − 3

2z = 3

Dividing both sides by 2, we obtain

z= 3/2

L.H.S = 4z + 3 = 4 × ( 3/) + 3 = 6 + 3 = 9

R.H.S = 6 + 2z = 6 + 2 × ( 3/) = 6 + 3 = 9

L.H.S. = R.H.S.

Hence, the result obtained above is correct.



Question 5:

Solve and check result: 2x − 1 = 14 − x

Answer:

2x − 1 = 14 − x

Transposing x to L.H.S and 1 to R.H.S, we obtain

2x + x = 14 + 1

3x = 15

Dividing both sides by 3, we obtain

x = 5

L.H.S = 2x − 1 = 2 × (5) − 1 = 10 − 1 = 9

R.H.S = 14 − x = 14 − 5 = 9

L.H.S. = R.H.S.

Hence, the result obtained above is correct.



Question 6:

Solve and check result: 8x + 4 = 3(x − 1) + 7

Answer:

8x + 4 = 3(x − 1) + 7

8x + 4 = 3x − 3 + 7

Transposing 3x to L.H.S and 4 to R.H.S, we obtain

8x − 3x = − 3 + 7 − 4

5x = − 7 + 7

x=0

L.H.S = 8x + 4 = 8 × (0) + 4 = 4

R.H.S = 3(x − 1) + 7 = 3 (0 − 1) + 7 = − 3 + 7 = 4

L.H.S. = R.H.S.

Hence, the result obtained above is correct.



Question 7:

Solve and check result: x = 4/( x + 10 )

Answer:

x = 4/( x + 10 )

Multiplying both sides by 5, we obtain

5x = 4(x + 10)

5x = 4x + 40

Transposing 4x to L.H.S, we obtain

5x − 4x = 40

x = 40

L.H.S = x = 40

RHS = x = 4/( x + 10 )= 4/( 40 + 10 ) = x = 4/( 50 ) = 40

L.H.S. = R.H.S.

Hence, the result obtained above is correct.


Question 8:

Solve and check result: 2x/+ 1 = 7x/15 + 3

Answer:

Transposing 7x/15 to L.H.S and 1 to R.H.S, we obtain

2x/7x/15= 3 - 1

3x/15  = 2

x/5  = 2

x=10

L.H.S = 2x/+ 1 = 2×10/+ 1 = 20+3/23/3

R.H.S = 7x/15 + 3 = 7×10/15 + 3 = ( 70 + 45 )/115/15 23/3

L.H.S. = R.H.S.

Hence, the result obtained above is correct.


Question 9:

Solve and check result: 2y + 5/26/- y

Answer:

2y + 5/26/- y

Transposing y to L.H.S and 5/to R.H.S, we obtain

2y + y 26/5/3

3y 21/3

3y 21/3

y 7/3

LHS= 2y + 5/= 2 × ( 7/) + 5/14/5/3  19/3

RHS = 26/- y 26/7/3 = = 19/3

L.H.S. = R.H.S.

Hence, the result obtained above is correct.


Question 10:

Solve and check result: 3m = 5m - 8/5

Answer:

3m = 5m - 8/5

Transposing 5m to L.H.S, we obtain

3m - 5m = - 8/5

-2m = - 8/5 Dividing both sides by −2, we obtain

m = 4/

L.H.S = 3m = 3 × 4/5 = 12/

R.H.S = 5m - 8/5 = 5 × 4/5 - 8/5  = 12/

L.H.S. = R.H.S.

Hence, the result obtained above is correct.