Algebraic Expressions and Identities — Maths STD 8 — Question
Maharashtra BoardEnglish MediumSTD 8MathsAlgebraic Expressions and Identities4 Marks
Question
Evaluate $\left(3.2 x^6 y^3\right) \times\left(2.1 x^2 y^2\right)$ when $x=1$ and $y=0.5$
✓
Answer
To multiply algebraic expressions, we use commutative and associative laws along with the law of indices, i.e. $a ^{ m } \times a ^{ n }$
$=a^{m+n}$.
$\left(3.2 x^6 y^3\right) \times\left(2.1 x^2 y^2\right)$
$=(3.2 \times 2.1) \times\left(x^6 \times x^2\right) \times\left(y^3 \times y^2\right)$
$=(3.2 \times 2.1) \times\left(x^{6+2}\right) \times\left(y^{3+2}\right)$
$=6.72 x^8 y^5$
Substituting $x=1$ and $y =0.5$ in the result,
we get:
$6.72 x^8 y^5$
$=6.72(1)^8(0.5)^5$
$=6.72 \times 1 \times 0.03125$
$=0.21$
Thus, the answer is 0.21 .
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