\(S=2^{100}-2^{99}+2^{98}-2^{97}+...+2^2-2\)
S= 100 ^ 2 - 99 ^ 2 + 98 ^ 2 - 97 ^ 2 +…+2^ 2 -1^ 2
\(S=100^2-99^2+98^2-97^2+...+2^2-1^2\)
\(S=\left(100^2-99^2\right)+\left(98^2-97^2\right)+...+\left(2^2-1^2\right)\)
\(S=\left(100-99\right)\left(99+100\right)+\left(98-97\right)\left(98+97\right)+...+\left(2-1\right)\left(2+1\right)\)
\(S=1\cdot199+1\cdot195+1\cdot193+...+1\cdot3\)
\(S=199+195+193+...+3\)
\(S=\left(3+199\right)\cdot\left[\left(199-3\right):2+1\right]:2\)
\(S=202\cdot99:2\)
\(S=101\cdot99\)
\(S=9999\)
Tính
S=1+2-3-4+5+6-7-8+9+10-11-12+........+97+98-99-100
A=2100-299+298-297+......+22-2
2^100-2^99+2^98-2^97+...+2^2-2
3^100-3^99+3^98-3^97+...+3^2-3+1
Giúp với các bạn ơi!!!
Tính:
a) A=2^100 - 2^99 + 2^98 - 2^97 + ... + 2^2 - 2
b) B=3^100 - 3^99 + 3^98 - 3^97 + ... + 3^2 - 3
s=1*2*3*4+2*3*4*5+....+97*98*99*100.tính s ik
S = 1.2.3.4 + 2.3.4.5 + 3.4.5.6+...97.98.99.100
5S = (1.2.3.4+2.3.4.5+3.4.5.6+ ... + 97.98.99.100).5
5S = 1.2.3.4.(5-0) + 2.3.4.5.(6-1)+ 3.4.5.6(7-2)+......+ 97.98.99.100.(101-96)
5S = (1.2.3.4.5 + 2.3.4.5.6 + 3.4.5.6.7 + ....+ 97.98.99.100.101) - (0.1.2.3.4 + 1.2.3.4.5 + 2.3.4.5.6+.....+96.97.98.99.100)
5S = 97.98.99.100.101
S= 97.98.99.100.101/5
S=1901009880
S=1*2*3*4+2*3*4*5+....+97*98*99*100
5S=1.2.3.4.5+2.3.4.5.5+...+97.98.99.100.5
5S=1.2.3.4.(5-0)+2.3.4.5.(6-1)+...+97.98.99.100.(101-96)
5S=1.2.3.4.5-0.1.2.3.4+2.3.4.5.6-1.2.3.4.5+...+97.98.99.100.101-96.97.98.99.100
5S=(1.2.3.4.5+2.3.4.5.6+...+97.98.99.100.101)-(0.1.2.3.4+1.2.3.4.5+...+96.97.98.99.100)
5S=97.98.99.100.101
S=9505049400:5=1901009880.
S = 1.2.3.4 + 2.3.4.5 + 3.4.5.6+...97.98.99.100
5S = (1.2.3.4+2.3.4.5+3.4.5.6+ ... + 97.98.99.100).5
5S = 1.2.3.4.(5-0) + 2.3.4.5.(6-1)+ 3.4.5.6(7-2)+......+ 97.98.99.100.(101-96)
5S = (1.2.3.4.5 + 2.3.4.5.6 + 3.4.5.6.7 + ....+ 97.98.99.100.101) - (0.1.2.3.4 + 1.2.3.4.5 + 2.3.4.5.6+.....+96.97.98.99.100)
5S = 97.98.99.100.101
S= 97.98.99.100.101/5
S=1901009880
a)A=1-2+3-4+...+99-100
b)B=1-2-3+4+5-6-7+...+97-98-99+100
c)C=2100-299s-998-...-22-2-1
giup mik vs a
A=-1++(-1)+..+-(1) có 50 số -1
=>A=-1x50=-50
B=(1-2-3+4)+(5-6-7+8)+...+(97-98-99+100)
B=0+0+0+..+0
B=0
C=2^100-(2^99+2^98+...+1)
C=2^100-(2^100-1)
C=1
S = -1 + ( -2 ) + 3 + 4 + ... + ( - 97 ) + ( - 98 ) + 99 + 100
Lời giải:
$S=[(-1)+(-2)+3+4]+[(-5)+(-6)+7+8]+....+[(-97)+(-98)+99+100]$
$=\underbrace{4+4+....+4}_{25}=4.25=100$
Rút gọn biểu thức
b) B=2^100-2^99+2^98-2^97+...+2^2-2
c) C=3^100-3^99+3^98-3^97+...+3^2-3+1
b) B = 2100 - 299 + 298 - 297 + ...+ 22 - 2
=> B x 2 = 2101 - 2100 + 299 - 298 + ...23 - 22
=> B x 2 + B = (2101 - 2100 + 299 - 298 + ...23 - 22 ) + (2100 - 299 + 298 - 297 + ...+ 22 - 2)
<=> B x 3 = 2101 - 2 = 2. ( 299 - 1)
=> B = \(\frac{2.\left(2^{99}-1\right)}{3}\)
Phần c) Làm tương tự Lấy C x 3 rồi + với C.
thu gọn các tổng :
A=2^100 - 2^99 +2^98 - 2^97 +...+ 2^2 - 2
B= 3^100 - 3^99 + 3^98 - 3^97 +...+ 3^2 - 3 +1
A = 2100 - 299 + 298 - 297 +...+ 22 - 2
=> 2A = 2101 - 2100+299 - 298+...+23-22
=> 2A+A= 2101 -2
=> \(A=\frac{2^{101}-2}{3}\)
phần B bn lm tương tự nha!