A = 1 + 1 x 2 + 1 x 2 x 3 + 1 x 2 x 3 x 4 + 1 x 2 x 3 x 4 x 5 + ........... + 1 x 2 x 3 x ....... x 100 .
ai giúp zới
a=(1+1/2) x ( 1+1/3) x (1+1/4) x (1+1/5) x (1+1/6)
giúp mik zới
\(A=\dfrac{3}{2}\times\dfrac{4}{3}\times\dfrac{5}{4}\times\dfrac{4}{5}\times\dfrac{5}{6}\)
\(A=\dfrac{7}{2}\)
\(A=\dfrac{3}{2}\times\dfrac{4}{3}\times\dfrac{5}{4}\times\dfrac{6}{5}\times\dfrac{7}{6}\\ A=\dfrac{7}{2}\)
a=(1+1/2) x ( 1+1/3) x (1+1/4) x (1+1/5) x (1+1/6)
\(A=\left(\dfrac{2}{2}+\dfrac{1}{2}\right)\times\left(\dfrac{3}{3}+\dfrac{1}{3}\right)\times\left(\dfrac{4}{4}+\dfrac{1}{4}\right)\times\left(\dfrac{5}{5}+\dfrac{1}{5}\right)\times\left(\dfrac{6}{6}+\dfrac{1}{6}\right)\)
\(A=\dfrac{3}{2}\times\dfrac{4}{3}\times\dfrac{5}{4}\times\dfrac{7}{5}=\dfrac{7}{2}\)
cú t ccau oiii ét ô ét giải giúp t bài này zới
4,7 : 0,25 + 5,3 x 4
3x ( a - 2) +150 = 240
1/9 + a + 7/12 = 17/18
( 1/2 x 1/3 + 1/3 x 1/4 + 1/4 x 1/5 + 1/5 x 1/6 + 1/6 x 1/7 + 1/7 x 1/8 ) x a = 9/16
\(4,7\div0,25+5,3\times4\)
\(=18,8+21,2\)
\(=40\)
\(3\times\left(a-2\right)+150=240\)
\(3\times\left(a-2\right)=90\)
\(a-2=30\)
\(a=32\)
\(\dfrac{1}{9}+a+\dfrac{7}{12}=\dfrac{17}{18}\)
\(\dfrac{1}{9}+a=\dfrac{13}{36}\)
\(a=\dfrac{1}{4}\)
\(\left(\dfrac{1}{2}\times\dfrac{1}{3}+\dfrac{1}{3}\times\dfrac{1}{4}+\dfrac{1}{4}\times\dfrac{1}{5}+\dfrac{1}{5}\times\dfrac{1}{6}+\dfrac{1}{6}\times\dfrac{1}{7}+\dfrac{1}{7}\times\dfrac{1}{8}\right)\times a=\dfrac{9}{16}\)
\(\left(\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+\dfrac{1}{5\times6}+\dfrac{1}{6\times7}+\dfrac{1}{7\times8}\right)\times a=\dfrac{9}{16}\)
\(\left(\dfrac{1}{2}-\dfrac{1}{8}\right)\times a=\dfrac{9}{16}\)
\(\dfrac{3}{8}\times a=\dfrac{9}{16}\)
\(a=\dfrac{3}{2}\)
Tính
a) (x-1/2)+(x-1/4)+(x-1/8)+...+(x-1/512)
Tìm x
a) (x-1/1×2)+(x-1/2×3)+...+(x-1/100×101)
b) (x-1)+(x-2)+(x-3)+...+(x-101)=5050
c) x+1/2+1/3+1/4+...+1/100=3/2+4/3+5/4++...+101/100
tìm chữ số tận cùng của A biết :
A = 1 x 2 + 1 x 2 x 3 + 1 x 2 x 3 x 4 + 1 x 2 x 3 x 4 x 5 + 1 x 2 x 3 x 4 x 5 x 6 +.......+ 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x 10 x 11 x...x 100 + ( 1 + 2 + 3 + 4 + 5 + 6 + 9 + 1 )
A.(x+1)+(x+2)+(x+3)+......(x+100)=5750
B. x+(1+2+3+4+5+..........+100)=2000
C.(x-1)+(x-2)-(x-3)+(x-4)+........(x-100)=50
Giúp mình với ạ mai mình phải nộp bài rồi
A. \(\left(x+1\right)+\left(x+2\right)+......+\left(x+100\right)=5750\)
\(x+1+x+2+....+x+100=5750\)
\(100x+\left(1+2+3+.......+100\right)=5750\)
\(100x+5050=5750\)
\(100x=700\)
\(x=700:100=7\)
B. x+(1+2+......+100) = 2000
x + 5050 = 2000
x = 2000 - 5050
x= -3050
C. ( x-1 )+(x-2)+......+( x - 100 ) = 50
x-1+x-2+.........+x-100 = 50
100x + ( -1-2-........-100 ) = 50
100x + ( - 5050 ) = 50
100x = 50 + 5050
100 x = 5100
x = 5100 : 100
x = 51
A . \(\left(x+1\right)+\left(x+2\right)+\left(x+3\right)+...+\left(x+100\right)=5750\)
\(\left(x+x+x+...+x\right)+\left(1+2+3+...+100\right)=5750\)
\(100x+5050=5750\)
\(100x=5750-5050\)
\(100x=700\)
\(\Rightarrow x=\frac{700}{100}=7\)
B. \(x+\left(1+2+3+4+5+....+100\right)=2000\)
\(x+\frac{\left(100+1\right).100}{2}=2000\)
\(x+5050=2000\)
\(\Rightarrow x=2000-5050=-3050\)
C. \(\left(x-1\right)+\left(x-2\right)+\left(x-3\right)+....+\left(x-100\right)=50\)
\(\left(x+x+x+...+x\right)-\left(1+2+3+...+100\right)=50\)
\(100x-5050=50\)
\(100x=5100\)
\(\Rightarrow x=\frac{5100}{100}=51\)
(2+4+6+...+100) - (1+3+5+...+99) = ?
1 x 2 + 2 x 3 + 3 x 4 + ... + 99 x 100 = ?
3 x 4 + 4 x 5 + 5 x 6 + ... + 149 x 150 = ?
1 + (1 + 2) + ( 1 + 2 + 3) + (1 + 2 + 3 + 4) + ....... + (1 + 2 + 3 + ... + 99)
----------------------------------------------------------------------------------------------------------- ( gạch ngang phân số )
1 x 99 + 2.98 + 3.97 + ...... + 99 x 1
Cho A = 1 x 2 + 2 x 3 + 3 x 4 + 4 x 5 + ... + 100 x 101
và B = 1 x 3 + 2 x 4 + 3 x 5 + 4 x 6 + ... + 100 x 102
Vậy B - A = ?
Ta có : A = 1.2 + 2.3 + 3.4 + ...... + 100.101
=> 3A = 1.2.3 - 1.2.3 + 2.3.4 - 2.3.4 + ...... + 100.101.102
=> 3A = 100.101.102
=> A = 100.101.102/3
=> A = 343400
1.Tìm x thuộc Z:
a)1+2+3+...+x=0
b)(x-1)+(x+1)+(x+2)+(x+3)+...+100=99
c)25.(x+5)=(7+3x)-(5x+4)
d)x.(x-1)-4(x+2)=3(2x-1)-x(4-x)
2.Tìm x thuộc Z:
a)(3-x).|3+x|=0
b)(x2+5).(x3+27)=0
c)(2x-4).(12-3x)>0
d)(x2-1).(x2+1).(x2+10).(x2+10).(x2+20)<0
3.Tìm a, b thuộc Z
a)a.(2b-1)=5
b)a2-a.b+b=7
c)a.(3b+1)+3(b-1)=10
d)2a+a.b-3b=11
Ai làm được câu nào thì cố giúp mình nhé mai phải nộp rồi!
1.Tìm x thuộc Z:
a)1+2+3+...+x=0
b)(x-1)+(x+1)+(x+2)+(x+3)+...+100=99
c)25.(x+5)=(7+3x)-(5x+4)
d)x.(x-1)-4(x+2)=3(2x-1)-x(4-x)
2.Tìm x thuộc Z:
a)(3-x).|3+x|=0
b)(x2+5).(x3+27)=0
c)(2x-4).(12-3x)>0
d)(x2-1).(x2+1).(x2+10).(x2+10).(x2+20)<0
3.Tìm a, b thuộc Z
a)a.(2b-1)=5
b)a2-a.b+b=7
c)a.(3b+1)+3(b-1)=10
d)2a+a.b-3b=11
Ai làm được câu nào thì cố giúp mình nhé mai phải nộp rồi!
biết rồi nhưng đăng ít thôi ko ko nhìn dc đề