# Ex.12.3 Q6 Algebraic Expressions Solution - NCERT Maths Class 7

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## Question

Simplify the expressions and find the value if $$x$$ is equal to $$2$$

(i) $$x + 7 + 4\left( {x - 5} \right)$$

(ii) $$3\left( {x + 2} \right) + 5x - 7$$

(iii) $$6x + 5\left( {x - 2} \right)$$

(iv) $$4\left( {2x - 1} \right) + 3x + 11$$

## Text Solution

What is Known?

Value of $$x$$

What is unknown?

Value of the given expressions.

Reasoning:

This is based on concept of simplification of like terms and then putting given value of variable and then performing the arithmetic operation as given in the question. Value of $$x$$ is given as $$2$$

Steps:

(i) $$x + 7 + 4\left( {x - 5} \right)$$

\begin{align}& =x+7+4x-20 \\ & =5x-13\text{ } \\ & \text{Now putting value of }x=2 \\ & 5x-13 \\ & =\left( 5\times 2 \right)-13 \\ & =10-13 \\ \text{ Ans} & =-3 \\ \end{align}

(ii) $$3\left( {x + 2} \right) + 5x - 7$$

\begin{align}&=3x+6+5x-7 \\&=8x-1\\ &\text{ Now putting value of }x=2 \\&=\left( 8\times 2 \right)-1 \\ &=16-1 \\\text{ Ans} &=15 \\\end{align}

(iii) $$6x + 5\left( {x - 2} \right)$$

\begin{align}& = 6x + 5x - 10\\& = 11x - 10\\&\text{ Now putting value of }x = 2\\& = \left( {11 \times 2} \right) - 10\\\text{ Ans} & = 12\end{align}

(iv) $$4\left( {2x - 1} \right) + 3x + 11$$

\begin{align}& = 8x - 4 + 3x + 11\\& = 11x + 7\\&\text{Now putting value of }x = 2\\ & = (11 \times 2) + 7\\ & = 22 + 7\\\text{ Ans} & = 29\end{align}

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