Finding the Unknown Class 7 Short Question Answer

Finding the Unknown Class 7 Short Question Answer

Finding the Unknown Class 7 Short Question Answer

Solve the following equations :

Question 1.

2(x + 4) = 12

Solution:

We have :

2(x + 4) = 12

or 2x + 8 = 12 [Simplifying the brackets on L.H.S.]

or 2x - 12 - 8 ['Transposing 8 to R.H.S.]

or 2x = 4

or [latex]\frac {2x}{2}[/latex] = [latex]\frac {4}{2}[/latex] [Dividing both sides by 2]

or x = 2.

Question 2.

3(n - 5) = 21

Solution:

We have :

3(n - 5) = 21

or [latex]\frac{3(n-5)}{3}[/latex] = [latex]\frac {21}{3}[/latex] [Dividing both sides by 3]

or n - 5 = 7

or n = 7 + 5 [Transposing - 5 to R.H.S.]

or n = 12.

Question 3.

3(n - 5) = - 21

Solution:

We have :

3(n - 5) = -21

or [latex]\frac{3(n-5)}{3}[/latex] = [latex]\frac {-21}{3}[/latex] [Dividing both sides by 3]

or n - 5 = - 7

or n = - 7 + 5 [Transposing - 5 to R.H.S.]

or n = - 2.

Question 4.

- 4(2 + x) = 8

Solution:

We have : - 4(2 + x) = 8

or - 8 - 4x - 8

or -8 + 8 - 4x = 8 + 8 or - 4x = 16

or [latex]\frac {-4x}{-4}[/latex] = [latex]\frac {14}{5}[/latex] or x = - 4.

Question 5.

4(2 - x) = 8

Solution:

We have : 4(2 - x) = 8

or 8 - 4x = 8

or 8 - 8 - 4x = 8 - 8 or - 4x = 0

or x = 0.