\(a,=x\left(x^2+2\right)\\ b,=2021\left(x+y\right)+x\left(x+y\right)=\left(x+2021\right)\left(x+y\right)\\ c,=49-\left(2x+y\right)^2=\left(7-2x-y\right)\left(7+2x+y\right)\)
a) x3+2x
= x(x2+2)
b) 2021x+2021y+x2+xy
= (2021x+2021y)+(x2+xy)
= 2021(x+y)+x(x+y)
= (2021+x)(x+y)
c) 49-4x2-4xy-y2
= -[(2x)2+2.2x.y+y2] + 72
= -(2x-y)2+72
= 72-(2x-y)2
= (7-2x+y)(7+2x-y)