Ex.12.3 Q8 Algebraic Expressions Solution - NCERT Maths Class 7

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Question

(i) If $$z = 10$$, find the value of $$z^3 – 3(z – 10)$$.

(ii) If $$p = \,– 10$$, find the value of $$p^2 – 2p\, – 100$$

Text Solution

Steps:

First simplify the expression

\begin{align}={{z}^{3}}-3z+30\end{align}

Now putting value of $$z=10$$

\begin{align} &={{\left( 10 \right)}^{3}}-\left( 3\times 10 \right)+30 \\&=1000-30+30 \\\text{ Ans } &=1000 \\\end{align}

(ii) If $$p = \,– 10$$, find the value of $$p^2 – 2p \,– 100$$

Put value of $$p = -10$$ to solve the expression

\begin{align}&= {\left( { - 10} \right)^2} - \left( {2 \times - 10} \right) - 100\\&= 100 + 20 - 100\\{\text{Ans}} &= 20\end{align}

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