(1^2+2^2+....+100^2).( 3^4 - 9 ^2)
Những câu hỏi liên quan
1+(-2)+3+(-4)+5+(-6)+7+(-8)+9+(-10)+11+(-12)=
-1+2+(-3)+4+(-5)+6+(-7)+8+(-9)+10+(-11)+12=
(-1)+(-2)+(-3)+(-4)+.......+(-99)+(-100)=
(-1)+2+(-3)+4+.......+(-99)+100=
1+(-2)+3+(-4)+........+99+(-100)=
lam la co tick nha
1+(-2)+3+(-4)+5+(-6)+7+(-8)+9+(-10)+11+(-12)
=(1+3+5+7+9+11)+[(-2)+(-4)+(-6)+(-8)+(-10)+(-12)]
= 36+-42
=-6
Đúng 0
Bình luận (0)
(-1)+2+(-3)+4+(-5)+6+(-7)+8+(-9)+10+(-11)+12
=[(-1)+(-3)+(-5)+(-7)+(-9)+(-11)]+(2+4+6+8+10+12)
=(-36)+42
=6
Đúng 1
Bình luận (2)
CMR
1/2-2/2^2+3/2^3-4/2^4+.....+99/2^99-100/2^100<2/9
CMR: A= 1/2-2/2^2+3/2^3-4/2^4+....+99/2^99-100/2^100<2/9
CMR: 1/2-2/2^2+3/2^3-4/2^4+.....99/2^99-100/2^100<2/9
chứng minhA=1/2-2/2^2+3/2^3-4/2^4+...+99/2^99-100/2^100<2/9
CMR A=1/2-2/2^2+3/2^3-4/2^4+...+99/2^99-100/2^100<2/9
Tính:
A=1+7+7^2 +7^3+..+7^2007
B=1+4+4^2+4^3+...+4^100
C=1+3^2+3^4+3^6+3^8+...+3^100
D=7+7^3+7^5+7^7+7^9+...+7^99
E=2+2^3+2^5+2^7+2^9+...+2^9009
\(A=1+7+7^2+7^3+...+7^{2007}\)
\(7A=7+7^2+7^3+7^4+...+7^{2008}\)
\(7A-A=\left(7+7^2+7^3+7^4+...+7^{2008}\right)-\left(1+7+7^2+7^3+...+7^{2007}\right)\)
\(6A=7^{2008}-1\)
\(A=\frac{7^{2008}-1}{6}\)
Tương tự, \(B=\frac{4^{101}-1}{3},C=\frac{3^{101}-1}{2}\).
\(D=7+7^3+7^5+7^7+...+7^{99}\)
\(7^2.D=7^3+7^5+7^7+7^9+...+7^{101}\)
\(\left(7^2-1\right)D=\left(7^3+7^5+7^7+7^9+...+7^{101}\right)-\left(7+7^3+7^5+7^7+...+7^{99}\right)\)
\(48D=7^{101}-7\)
\(D=\frac{7^{101}-7}{48}\)
Tương tự, \(E=\frac{2^{9011}-2}{3}\)
bài 1
A=1*2*3+2*3*4+3*4*5+...+99*100*101
B=1*3*5+3*5*7+...+95*97*99
C=2*4+4*6+..+98*100
D=1*2+3*4+5*6+...+99*100
E=1^2+2^2+3^2+...+100^2
G=1*3+2*4+3*5+4*6+...+99*101+100*102
H=1*2^2+2*3^2+3*4^2+...+99*100^2
I=1*2*3+3*4*5+5*6*7+7*8*9+...+98*99*100
K=1^2+3^2+5^2+...+99^2
A = 1*2*3 + 2*3*4 + 3*4*5 ... + 99*100*101
=> 4A = 1*2*3*4 + 2*3*4*4 + 3*4*5*4 + ... +99*100*101*4
=> 4A = 1*2*3*4 + 2*3*4*(5 - 1) + 3*4*5*( 6 - 2) + ... + 99*100*101*(102 - 98)
=> 4A = 1*2*3*4 + 2*3*4*5 - 1*2*3*4 + 3*4*5*6 - 2*3*4*5 + ... + 99*100*101*102 - 98*99*100*101
=> 4A = 99*100*101*102
=> 4A = 101989800
=> A = 25497450
chứng minh rằng
A:1/2+2/2^2+3/2^3+4/2^4+...+100/2^100<2/9
CMR
1/2-2/2^2+3/2^3-4/2^4+.....+99/2^99-100/2^100<2/9