\(A=1+3+3^2+3^3+...+3^{2021}\)
=>\(3\cdot A=3+3^2+3^3+...+3^{2022}\)
=>\(3A-A=3+3^2+3^3+...+3^{2022}-1-3-3^2-...-3^{2021}\)
=>\(2A=3^{2022}-1\)
=>\(A=\dfrac{3^{2022}-1}{2}\)
cho a^1/a^2=a^2/a^3=.......=a^2021/a^2021
cmr:a^1/a^2021=(a^1+a^2+.....+a^2020/a^2+a^3+.....+a^2021)^2020
a,3/7.19/15-3/7.12/15 b,1/5+(-1/3)ᒾ.√81/25 c,(-1/2)³:3/8+|-2/3|-2021⁰
A=1*2+2*3+3*4+...+2020*2021
tính A=1/2!+2/3!+3/4!+...+2021/2022!
Cho x , y , z đồng thời thỏa mãn x + y + z = 1 ; x^2 + y^2 + z^2 = 1 ; x^3 + y^3 + z^3 = 1
Tính x^2021 + y^2021 + z^2021
1. So sánh
a) \(A=\dfrac{1}{2}+\dfrac{1}{2^2}+\dfrac{1}{2^3}+...+\dfrac{1}{2^{2020}}+\dfrac{1}{2^{2021}}\) và B= \(\dfrac{1}{3}+\dfrac{1}{4}+\dfrac{1}{5}+\dfrac{13}{60}\)
b) \(C=\dfrac{2019}{2021}+\dfrac{2021}{2022}\) và \(D=\dfrac{2020+2022}{2019+2021}.\dfrac{3}{2}\)
Cho x , y , z đồng thời thỏa mãn x + y + z = 1 ; x^2 + y^2 + z^2 = 1 ; x^3 + y^3 + z^3 = 1
Tính x^2021 + y^2021 + z^2021
a,7/4+-3/5
b,2021-(1/3)^2 x 3^2
c,7,5 x(-3/5)
d,(-1/4)^2 x 4/11+7/11 x(-1/4)^2
e, A= 1/4 +1/4^2+1/4^3+...+1/4^2020<1/3
