Question

$4a ^{2} - b ^{2} - 9c ^{2} + 6bc$
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Answer 1

Step-by-step explanation:

$4a {}^{2} - b {}^{2} - 9c {}^{2} + 6bc \\ = 4a {}^{2} - (b {}^{2} - 6bc + 9c {}^{2} ) \\ = (2a) {}^{2} - (b - 3c) {}^{2} \\ = (2a + b - 3c)(2a - b + 3c)$