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Identities — MATHS STD 8 — Question

ICSE BoardEnglish MediumSTD 8MATHSIdentities4 Marks
Question
Use the direct method to evaluate : $\left(\frac{3}{5} a+\frac{1}{2}\right)\left(\frac{3}{5} a-\frac{1}{2}\right)$
✓

Answer

Note : $(a+b)(a-b)=a^2-b^2$
$\left(\frac{3}{5} a+\frac{1}{2}\right)\left(\frac{3}{5} a-\frac{1}{2}\right)$
$ =\left(\frac{3}{5} a\right)^2-\left(\frac{1}{2}\right)^2$
$ =\frac{9}{25} a^2-\frac{1}{4}$

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