q 解:支反力RA=RB= R R B 2 M(x RRi n e() Q 2 M=x-x 22 Q l/2 q M q max 2 max 8 -ql/2 M /8Q(x) M(x) x RA n Q − ql / 2 ql / 2 /8 2 ql M q l RA RB 解：支反力 2 ql RA = RB = qx ql Q = − 2 2 2 2 x q x ql M = − 2 max ql Q = 8 2 max ql M =