根据题意哟：
a-1=0;
a=1;
b+4=0;
b=-4;
原式=1/(1×(-4))+1/(1+3)(-4+3)+1/(1+6)(-4+6)+1/(1+9)(-4+9)
=-1/4-1/4+1/14+1/50
=-1/2+50/700+14/700
=-350/700+64/700
=-286/700
=-143/350;
很高兴为您解答,skyhunter002为您答疑解惑
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