Use the Euler equation from Problem 4-11 to find extremals for the func- tionals: x(0)-0, x(0)-1, (x)=(x(1)()+³(r)] dt; x(1) 2, (1)=4. (a) x(0) 1, (0) 2, x(00)=0, *(0) = 0. (b) (x) = (³(1) + x*(c) + [*(c) + 2(c)]³} dr; }