Use the direct method to evaluate : (0.5a−2a) (0.5+2a) - Vidyadip

Question

Use the direct method to evaluate : $(0.5a−2a) (0.5+2a)$

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Answer

$(a+b) (a−b) = a^2 − b^2(0.5a−2a) (0.5+2a)$
$= (0.5)^2 − (2a)^2$
$= 0.25 − 4a^2$

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