Question

高三数学 求详细过程

Answer 1

(2x-m)^7=a0+a1.(1-x)+a2.(1-x)^2+....+a7(1-x)^7
x=1/2
(1-m)^7 = a1+a1/2+a2/2^2+....+a7/2^7 = -128
(1-m)^7 =-128
1-m=-2
m=3
m=3
(2x-3)^7=a0+a1.(1-x)+a2.(1-x)^2+....+a7(1-x)^7
= a0+(-1)^1.a1.(x-1) +(-1)^2. a2.(x-1)^2+.....+(-1)^7.a7.(x-1)^7
f(x) =(2x-3)^7 =>f(1) = -1
f'(x) =14(2x-3)^6 => f'(1)/1! = 14
f''(x) =168(2x-3)^5 => f''(1)/2! =-84
f'''(x) =1680(2x-3)^4 =>f'''(1)/3! = 280
(-1)^3 .a3 = f'''(1)/3!
-a3 = 280
a3 =-280

Answer 2

数列an是等比数列吗？