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

Nov 6, 2014

$4 {a}^{2} - 8 a b - 9 {b}^{2} - \left(5 {b}^{2} - 2 {a}^{2}\right)$

by distributing the negative sign,

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

by grouping the like terms,

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

by simplifying a bit further,

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

I hope that this was helpful.