# Ex.9.1 Q4 Algebraic Expressions and Identities - NCERT Maths Class 8

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## Question

(a) Subtract $$4a - 7ab + 3b + 12$$ from

$$12a - 9ab + 5b - 3$$

(b) Subtract $$3xy + 5yz - 7zx$$ from

$$5xy - 2yz - 2zx + 10xyz$$

(c) Subtract $$\begin{Bmatrix}4{p^2}q - 3pq + 5p{q^2} \\ - 8p + 7q - 10\end{Bmatrix}$$ from

$$\begin{Bmatrix}18 - 3p - 11q +\\ 5pq - 2p{q^2} + 5{p^2}q\end{Bmatrix}$$

Video Solution
Algebraic Expressions & Identities
Ex 9.1 | Question 4

## Text Solution

What is known?

Expressions

What is unknown?

Subtraction

Reasoning:

Subtraction will take place between like terms.

Steps:

The given expressions in separate rows, with like terms one below the other and

then the subtraction of these expressions is as follows.

(a)

\dfrac{\begin{align}&12a\,\,\,\,\,\, - 9ab\,\,\,\,\,\, + 5b\,\,\,\,\,\, - 3\\&4a\,\,\,\,\,\, - 7ab\,\,\,\,\,\, + 3b\,\,\,\,\,\,\, + 12\\&\left(-\right)\,\,\,\,\,\,\,\,\left(+\right)\,\,\,\,\,\,\,\,\,\,\,\left(-\right)\,\,\,\,\,\,\,\,\,\,\left(-\right)\end{align}}{{\!\!\!\!\!\!\!\!8a - 2ab\,\,\,\, + 2b - 15}}

(b)

\dfrac{\begin{align}&5xy - 2yz - 2zx + 10xyz\\&3xy + 5yz - 7zx\\&\left(-\right)\,\,\,\,\,\,\,\,\left(-\right)\,\,\,\,\,\,\left(+\right)\end{align}}{{\,\,\,\,\,\,\,2xy - 7yz + 5zx + 10xyz}}

(c)

\dfrac{\begin{align}18 - 3p\! - 11q \!+\! 5pq \!- 2p{q^2} \!+ \!5{p^2}q \\ - 10 - 8p +\! 7p\! - \!3pq +\! 5p{q^2} + \!4{p^2}q\\\left(+\right)\,\,\,\,\left(+\right)\,\,\,\,\left(-\right)\,\,\,\,\,\,\left(+\right)\,\,\,\,\left(-\right)\,\,\,\,\,\left(-\right)\,\,\,\,\;\end{align}}{28\!+\!5p \!- \!18q \!+\! 8pq \!- \!7p q^2\! +\! p^2 q}

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