X - 101 = 99
2/x*(x+2)+2/3*5+2/5*7+...2/99*101=100/101
\(\frac{2}{x.\left(x+2\right)}+\frac{2}{3.5}+\frac{2}{5.7}.+.....+\frac{2}{99.101}=\frac{100}{101}\)
\(\Rightarrow\frac{1}{x\left(x+1\right)}+\frac{1}{3.5}+\frac{1}{5.7}+....+\frac{1}{99.101}=\frac{100}{101}\)
\(\Rightarrow\frac{1}{x}-\frac{1}{x+1}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+....+\frac{1}{99}-\frac{1}{101}=\frac{100}{101}\)
\(\Rightarrow\frac{1}{x}-\frac{1}{101}=\frac{100}{101}\)
\(\Rightarrow\frac{1}{x}=\frac{101}{101}\)
\(\Rightarrow\frac{1}{x}=\frac{1}{1}\)
\(\Rightarrow x=1\)
( 145 x 99 + 145 ) - ( 143 x 101 - 143 )
Phân phối:
= ( 145 x 99 + 145 x 1 ) - ( 143 x 101 - 143 x 1 )
= 145 x (99 + 1) - [143 x (101 - 1)]
= 145 x 100 - 143 x 100
= (145 - 143) x 100
= 2 x 100 = 200
[ 234 x 99 + 234 ] - [34 x 101 - 34 ]
x + 99 = 99 + 100 + 101
Ai kik tớ tớ kik lại !
x + 99 = 99 + 100 + 101
x + 99 = 199 + 101
x + 99 = 300
x = 300 - 99
x = 201.
x + 99 = 99 + 100 + 101
x + 99 = 199 + 101
x + 99 = 300
x = 300 - 99
x = 201
Vậy x = 201
/x-99/^100+/x-100/^101=1
So sánh : 99 x 101 ; 100 x 100
Xét 99 x 101
= ( 100 - 1 ) x ( 101 - 1 )
= 100 x 100 + 1 x 101 - 1 x 101 - 1 x 1
= 100 x 100 - 1
Vậy 99 x 101 < 100 x 100
nhầm chút
Xét 99 x 101
= ( 100 - 1 ) x ( 100 + 1 )
= 100 x 100 + 1 x 101 - 1 x 101 - 1 x 1
= 100 x 100 - 1
Vậy 99 x 101 < 100 x 100
Tính nhanh : ( 145 x 99 + 145 ) - ( 143 x 101 - 143 )
=145x(99+1)-143x(101-1)
=145x100 - 143x100
=100x(145-143)
=100x2
=200
[145 x 99+145]-[149 x 101 -143]\4x113x25-5x112x20
tìm x để: |x - 99|^100 + |x - 100|^101 =1