# What should be taken away from 3x^{2} – 4y^{2} + 5xy + 20 to obtain - x^{2} – y^{2} + 6xy + 20?

**Solution:**

We will be using the concept of addition and subtraction of algebraic expressions to solve the given question.

Let us assume the missing part as X.

Therefore according to the question,

(3x^{2} - 4y^{2} + 5xy + 20) - (X) = - x^{2} - y^{2} + 6xy + 20

Let us shift the terms to find the value of X

X = 3x^{2} - 4y^{2} + 5xy + 20 - (- x^{2} - y^{2} + 6xy + 20)

X = 3x^{2} - 4y^{2} + 5xy + 20 + x^{2} + y^{2} - 6xy - 20

X = 4x^{2} - 3y^{2} - xy

Thus, the expression that should be subtracted is 4x^{2} - 3y^{2} - xy.

**Video Solution:**

## What should be taken away from 3x² – 4y² + 5xy + 20 to obtain -x² – y² + 6xy + 20?

### Maths NCERT Solutions Class 7 - Chapter 12 Exercise 12.2 Question 5

**Summary:**

4x^{2} - 3y^{2} - xy should be taken away from 3x^{2} - 4y^{2} + 5xy + 20 to obtain - x^{2} - y^{2} + 6xy + 20.