(i) a2+4b2a^2 + 4b^2a2+4b2 Solution Write as difference of squares:a2+4b2=a2−(−4b2)=a2−(2ib)2Factor:=(a−2ib)(a+2ib)\begin{aligned} & \boxed{\text{Write as difference of squares:}} \\ \\ & a^2 + 4b^2 = a^2 - (-4b^2) = a^2 - (2ib)^2 \\ \\ & \boxed{\text{Factor:}} \\ \\ & = (a - 2ib)(a + 2ib) \end{aligned}Write as difference of squares:a2+4b2=a2−(−4b2)=a2−(2ib)2Factor:=(a−2ib)(a+2ib)