# (a) From the sum of 3x – y + 11 and – y – 11, subtract 3x – y – 11.

(b) From the sum of 4 + 3x and 5 – 4x + 2x^{2} , subtract the sum of 3x^{2} – 5x and - x^{2} + 2x + 5.

**Solution:**

Let's use the concept of addition and subtraction of algebraic expressions to solve the given questions.

(a) From the sum of 3x - y + 11 and - y - 11, subtract 3x - y -11

First, we add 3x - y + 11 and - y - 11

= 3x - y + 11 + (- y - 11)

= 3x - y + 11 - y - 11

= 3x - 2y

Now from 3x - 2y subtract 3x - y - 11

= 3x - 2y - (3x - y - 11)

= 3x - 2y - 3x + y + 11

= - y + 11

(b) From the sum of 4 + 3x and 5 – 4x + 2x^{2} , subtract the sum of 3x^{2} – 5x and - x^{2} + 2x + 5

Add 4 + 3x and 5 - 4x + 2x^{2}

= 4 + 3x + 5 - 4x + 2x^{2}

= 2x^{2} - x + 9

Now add 3x^{2} - 5x and - x^{2} + 2x + 5

= 3x^{2} - 5x + ( - x^{2} + 2x + 5)

= 3x^{2} - 5x - x^{2} + 2x + 5

= 2x^{2} - 3x + 5

Now subtract 2x^{2} - 3x + 5 from 2x^{2} - x + 9

= 2x^{2} - x + 9 - (2x^{2} - 3x + 5)

= 2x^{2} - x + 9 - 2x^{2} + 3x - 5

= 2x + 4

**☛ Check: **NCERT Solutions for Class 7 Maths Chapter 12

**Video Solution:**

## (a) From the sum of 3x – y + 11 and - y – 11, subtract 3x – y – 11. (b) From the sum of 4 + 3x and 5 – 4x + 2x², subtract the sum of 3x² – 5x and - x² + 2x + 5.

Maths NCERT Solutions Class 7 Chapter 12 Exercise 12.2 Question 6

**Summary:**

(a) From the sum of 3x – y + 11 and - y – 11, when 3x – y – 11 is subtracted, we get - y + 11. (b) From the sum of 4 + 3x and 5 – 4x + 2x^{2}, when the sum of 3x^{2} – 5x and - x^{2} + 2x + 5 is subtracted, we get 2x + 4.

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