a) (x+4y)(4y-x)= x4y + x(-x) + 4y4y + 4y(-x)= 4xy - x^2 + 16y^2 - 4xy= - x^2 + 16y^2
b) 2t(t+8)-(t-6)^2= 2t^2 + 16t - (t^2 - 12t + 36)= 2t^2 + 16t - t^2 + 12t - 36= t^2 + 28t - 36
a) (x+4y)(4y-x)
= x4y + x(-x) + 4y4y + 4y(-x)
= 4xy - x^2 + 16y^2 - 4xy
= - x^2 + 16y^2
b) 2t(t+8)-(t-6)^2
= 2t^2 + 16t - (t^2 - 12t + 36)
= 2t^2 + 16t - t^2 + 12t - 36
= t^2 + 28t - 36