Question

what must be subtracted from
$3 {a}^{2} + 4 {b}^{2} - 6ab \:$
to get
$8 {b}^{2} - 4 {a}^{2} + 2ab$
?​

Answer 1

Step-by-step explanation:

The term to be subtracted from

$3 {a}^{2} + 4 {b}^{2} - 6ab \:$

to get

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

=

$3 {a}^{2} + 4 {b}^{2} - 6ab \: - ( 8 {b}^{2} - 4 {a}^{2} + 2ab) \\ = 3 {a}^{2} + 4 {b}^{2} - 6ab \: - 8 {b}^{2} + 4 {a}^{2} - 2ab) \\ = 7 {a}^{2} - 4 {b}^{2} - 8ab$