# Ex.12.3 Q1 Algebraic Expressions Solution - NCERT Maths Class 7

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## Question

If $$m = 2$$, find the value of:

(i)  $$m = 2$$

(ii) $$3m - 5$$

(iii) $${\rm{ }}9{\rm{ }}-{\rm{ }}5m$$

(iv) $$3{m^2} - 2m - 7$$

(v) \begin{align} \frac{{5m}}{2} - 4\end{align}

Video Solution
Algebraic Expressions
Ex 12.3 | Question 1

## Text Solution

What is Known?

Value of $$m$$.

What is unknown?

Value of the given expressions.

Reasoning:

This is based on concept of putting given value of variable and then performing the arithmetic operation as given in the question.

Steps:

Value of $$m$$ is given as $$2$$.

(i)  $$m = 2$$

\begin{align}& {\rm{ = 2}} - {\rm{2}}\\{\rm{ Ans }} &\,{\rm{ = }}\,{\rm{0 }}\end{align}

(ii) $$3m - 5$$

\begin{align}& = 3 \times 2 - \left( 5 \right)\\& = 6 - 5\\{\rm{ Ans }} &= 1\end{align}

(iii) $${\rm{ }}9{\rm{ }}-{\rm{ }}5m$$

\begin{align}& = 9 - \left( {5 \times 2} \right)\\& = 9 - 10\\{\rm{ Ans }} &= - 1\end{align}

(iv) $$3{m^2} - 2m - 7$$

\begin{align}& = 3{{\left( 2 \right)}^2} - \left( {2 \times 2} \right) - 7\\& = 3 \times 2 \times 2 - \left( 4 \right) - 7\\& = 12 - 4 - 7\\{\rm{ Ans }} & = 1\end{align}

(v) \begin{align} \frac{{5m}}{2} - 4\end{align}

\begin{align}& = \frac{{5 \times 2}}{2} - 4\\& = \frac{{10}}{2} - 4\\& = 5 - 4\\{\rm{ Ans }} & = 1\end{align}

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