Algebraic Expressions and Identities — Maths STD 8 — Question
Maharashtra BoardEnglish MediumSTD 8MathsAlgebraic Expressions and Identities4 Marks
Question
Evaluate $\left(2.3 a ^5 b^2\right) \times\left(1.2 a ^2 b^2\right)$ when $a =1$ and $b =0.5$.
✓
Answer
To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e. $a^m \times a^n$
$=a^{m+n} .\left(2.3 a^5 b^2\right) \times\left(1.2 a^2 b^2\right)$
$=(2.3 \times 1.2) \times\left(a^5 \times a^2\right) \times\left(b^2 \times b^2\right)$
$=(2.3 \times 1.2) \times\left(a^5+2\right) \times\left(b^2+2\right)$
$=2.76 a^7 b^4$
$\left(2.3 a^5 b^2\right) \times\left(1.2 a^2 b^2\right)=2.76 a^7 b^4$
Substituting $a=1$ and $b=0.5$ in the result, we get: $2.76 a^7 b^4$
$=2.76(1)^7(0.5)^4$
$=2.76 \times 1 \times 0.0625$
$=0.1725$
Thus, the answer is $=0.1725$
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