Multiply each term in the expression by the whole expression and add like terms. For example

x + 2y + 2z)^2 = (x + 2y + 2z)*(x + 2y + 2z)Multiplying the first term (x) by the full expression (x + 2y + 2z) getx^2 + 2xy + 2xz (a)Now do the same with the second term (2y)2xy + 4*y^2 + 4*y*z (b)and finally the last term (2z)2xz + 4zy + 4z^2 (c)Then add them all [(a) + (b) + (c)] together and collect like terms.