(1)2+4+6+8+.+100= (2)已知d=-3份之1,a7=8,求a1
1个回答
1.2550
(2+100)*(50/2)
2.
a7=a1+(-1/3)*7
a7=8
a1=8+7/3=31/3
相关问题
1.已知数列{an}为等差数列(1)a1=1,d=4,求a20;(2)a1=6,a8=27,求d;(3)a3=8,a7=
已知全集∪={1,2,3,4,5,6,7,8},A={1,2,4},B={2,4,5},P={4,7,8},求:
1.已知³√a+b=2,³√a-1=-1,求(6b-8a)¹+...+(6b-8a)100
已知d=-1/3 ,a7=8,求a1
已知集合A={1,2,3,4} B={3,4,5,6,7} C={6,7,8,9} 求(1)A∩B A∩B∩C (2)A
已知全集U={0,1,2,3,4,5,6,7,8},集合A={0,1,2,3},集合8={2,3,4,5,6} 求(1)
等差数列 1.已知a1=3 a10=43 求S10 2.已知a1=100 d=-2 求S50 3.已知a5=8 a9=2
已知全集U= {1,2,3,4,5,6,7,8 },A= {3,4,5 },B={1,3,6 },那么集合{ 2,7,8
已知A=1/2*3/4*5/6*7/8*.*99/100,B=1/10,那么谁大?
已知集合A={1,2,3,4},B={2.4,6},全集U={1,2,3,4,5,6,7,8}:求A倒UB,AUB,