a) a^4 +a^2b^2 +b^4 = add and subtract a^2*b^2 = (a^4 + 2a^2*b^2 + b^4) - a^2*b^2 =- = apply the formula - = (x+y)*(x-y) = . ANSWER
b) a^4 + 4b^4 = a^4 + (2b^2)^2 = add and subtract 2*a^2*(2b^2) = (a^4 + 2*a^2*(2b^2) + 4b^4) - 2*a^2*(2b^2) = = (a^2 + 2b^2)^2 - 4*a^2*b^2 = = (a^2 + 2b^2)^2 - (2ab)^2 = apply the formula- = (x+y)*(x-y) = (a^2 - 2ab + 2b^2)*(a^2 + 2ab + 2b^2).