1.若代数式1/2(X+1)+1/6(X+1)+1/12(X+1)...+1/1980(X+1)+1/2070(X+1)的值是45,试问X的值是多少?(1/2=二分之一......)2.若规定两数a,b通过"※"运算,得到4ab,即a※b=4ab,2※6=4×2×6=48(1)求3※5.(2)无论x是什么
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![1.若代数式1/2(X+1)+1/6(X+1)+1/12(X+1)...+1/1980(X+1)+1/2070(X+1)的值是45,试问X的值是多少?(1/2=二分之一......)2.若规定两数a,b通过](/uploads/image/z/3701380-4-0.jpg?t=1.%E8%8B%A5%E4%BB%A3%E6%95%B0%E5%BC%8F1%2F2%28X%2B1%29%2B1%2F6%28X%2B1%29%2B1%2F12%28X%2B1%29...%2B1%2F1980%28X%2B1%29%2B1%2F2070%28X%2B1%29%E7%9A%84%E5%80%BC%E6%98%AF45%2C%E8%AF%95%E9%97%AEX%E7%9A%84%E5%80%BC%E6%98%AF%E5%A4%9A%E5%B0%91%3F%281%2F2%3D%E4%BA%8C%E5%88%86%E4%B9%8B%E4%B8%80......%292%EF%BC%8E%E8%8B%A5%E8%A7%84%E5%AE%9A%E4%B8%A4%E6%95%B0a%2Cb%E9%80%9A%E8%BF%87%22%E2%80%BB%22%E8%BF%90%E7%AE%97%2C%E5%BE%97%E5%88%B04ab%2C%E5%8D%B3a%E2%80%BBb%3D4ab%2C2%E2%80%BB6%3D4%C3%972%C3%976%EF%BC%9D48%EF%BC%881%EF%BC%89%E6%B1%823%E2%80%BB5%EF%BC%8E%EF%BC%882%EF%BC%89%E6%97%A0%E8%AE%BAx%E6%98%AF%E4%BB%80%E4%B9%88)
1.若代数式1/2(X+1)+1/6(X+1)+1/12(X+1)...+1/1980(X+1)+1/2070(X+1)的值是45,试问X的值是多少?(1/2=二分之一......)2.若规定两数a,b通过"※"运算,得到4ab,即a※b=4ab,2※6=4×2×6=48(1)求3※5.(2)无论x是什么
1.若代数式1/2(X+1)+1/6(X+1)+1/12(X+1)...+1/1980(X+1)+1/2070(X+1)的值是45,试问X的值是多少?
(1/2=二分之一......)
2.若规定两数a,b通过"※"运算,得到4ab,即a※b=4ab,2※6=4×2×6=48
(1)求3※5.
(2)无论x是什么数时,总有a※x=x,求a的值.
1.若代数式1/2(X+1)+1/6(X+1)+1/12(X+1)...+1/1980(X+1)+1/2070(X+1)的值是45,试问X的值是多少?(1/2=二分之一......)2.若规定两数a,b通过"※"运算,得到4ab,即a※b=4ab,2※6=4×2×6=48(1)求3※5.(2)无论x是什么
1.1/2(X+1)+1/6(X+1)+1/12(X+1)...+1/1980(X+1)+1/2070(X+1)
=1/(1+x)*(1/2+1/6+...+1/2070)
=1/(1+x)*(1/2+1/(2*3)+1/(3*4)+...+1/(45*46))
=1/(1+x)*((1-1/2)+(1/2-1/3)+(1/3-1/4)+...+(1/45-1/46))
=1/(1+x)*(1-1/46)
=(45/46)/(1+x)
=45
So x=-45/46
2.(1) 60
(2) a※0=4a*0=0 =a So a=0.
楼上的2(2)有问题吧
不能透过代入一个定值计算
a※x=4ax=x
4a=1
a=1/4