2.14 Use algebraic manipulation to find the minimum product-of-sums expression for the func- tion f(x1+x3 + x4) (x1+x2+x3) (x1+2+3+x4). = 2.68 Repeat Problem 2.66 for the following expressions f = x2x3x4+X2x3 + x2x4+x1x2x4 +35 8 = (x2+x3 + x4)(x2+x4+xs)(x1+x2+3)(x2+x3+4+5)