1.For r=0,1,…,10r = 0, 1, \ldots, 10r=0,1,…,10, let Ar,BrA_r, B_rAr,Br and CrC_rCr denote the coefficient of xrx^rxr in the expansions of (1+x)10(1+x)^{10}(1+x)10, (1+x)20(1+x)^{20}(1+x)20 and (1+x)30(1+x)^{30}(1+x)30 respectively. Then ∑r=110Ar(B10Br−C10Ar)\sum_{r=1}^{10} A_r (B_{10} B_r - C_{10} A_r)∑r=110Ar(B10Br−C10Ar) is equal toa.B10−C10B_{10} - C_{10}B10−C10b.A10(B102−C10A10)A_{10} (B_{10}^2 - C_{10} A_{10})A10(B102−C10A10)c.0d.C10−B10C_{10} - B_{10}C10−B10Login to continueOnly logged in users canattempt or see the solution.
