How do you subtract $5 b^{2} - 2 a^{2}$ $5b^2-2a^2$ from $4 a^{2} - 8 a b - 9 b^{2}$ $4a^2-8ab-9b^2$ ?

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Answer 1 · 2014-11-06T18:05:56

$4 a^{2} - 8 a b - 9 b^{2} - (5 b^{2} - 2 a^{2})$ $4a^2-8ab-9b^2-(5b^2-2a^2)$

by distributing the negative sign,

$= 4 a^{2} - 8 a b - 9 b^{2} - 5 b^{2} + 2 a^{2}$ $=4a^2-8ab-9b^2-5b^2+2a^2$

by grouping the like terms,

$= (4 a^{2} + 2 a^{2}) - 8 a b + (- 9 b^{2} - 5 b^{2})$ $=(4a^2+2a^2)-8ab+(-9b^2-5b^2)$

by simplifying a bit further,

$= 6 a^{2} - 8 a b - 14 b^{2}$ $=6a^2-8ab-14b^2$

I hope that this was helpful.

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