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

Go back to  'Ex.9.1'

## Question

(a) Subtract $$4a - 7ab + 3b + 12$$ from $$12a - 9ab + 5b - 3$$

(b) Subtract $$3xy + 5yz - 7zx$$ from $$5xy - 2yz - 2zx + 10xyz$$

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

$$18 - 3p - 11q + 5pq - 2p{q^2} + 5{p^2}q$$

## 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)

\frac{\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)

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

(c)

\frac{\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}}

Learn from the best math teachers and top your exams

• Live one on one classroom and doubt clearing
• Practice worksheets in and after class for conceptual clarity
• Personalized curriculum to keep up with school