Help pls

[flat token]

i used u sub x+y

so now i have 70u^2 -yu -6y^2

what i do now?

[lapis heron]

bro

what is the question asking u to do

[ripe sand]

bro there’s no need for substitution,all you need is to expand the formula then add together.btw (x+y)^2=x^2+y^2+2xy

[bleak narwhal]

@flat token is it just collecting like terms?

[flat token]

The question I asking me to use substitution

Is*