A = 8/11 + 5/7 - 3/11 + 2/7 + 6/11
A = 8/11 + 5/7 - 3/11 + 2/7 + 6/11
A=(\(\dfrac{8}{11}-\dfrac{3}{11}+\dfrac{6}{11}\))+(\(\dfrac{5}{7}+\dfrac{2}{7}\))
A=\(\dfrac{11}{11}\)+\(\dfrac{7}{7}\)
A=1+1
A=2
mọi người giúp em với ạ. em cảm ơn
x-1phần 4=5 phần 3 ×4 phần 9
\(\dfrac{x-1}{4}=\dfrac{5}{3}.\dfrac{4}{9}\Leftrightarrow\dfrac{x-1}{4}=\dfrac{20}{27}\Rightarrow27x-27=80\)
\(\Leftrightarrow27x=107\Leftrightarrow x=\dfrac{107}{27}\)
x-1phần 4=5 phần 3 ×4 phần 9 giải giúp đi mai tui thi rùi
\(x-\dfrac{1}{4}=\dfrac{5}{3}\times\dfrac{4}{9}\\ \Rightarrow x-\dfrac{1}{4}=\dfrac{20}{27}\\ \Rightarrow x=\dfrac{20}{27}+\dfrac{1}{4}\\ \Rightarrow x=\dfrac{107}{108}\)
5/6×16 3/4-5/6×10 3/4
Tìm x, biết: 3/x-5 = -4/x+2
\(\dfrac{3}{x-5}=\dfrac{-4}{x+2}\)
\(\Rightarrow3.\left(x+2\right)=\left(x-5\right).\left(x-2\right)\)
\(\Rightarrow3.x+3.2=x.\left(-4\right).-5.\left(-4\right)\)
\(\Rightarrow3x+6=-4x-\left(-20\right)\)
\(\Rightarrow3x=6=-4x+20\)
\(\Rightarrow3x+4x=20-6\)
\(\Rightarrow7x=14\)
\(\Rightarrow x=2\)
\(\dfrac{3}{x-5}=-\dfrac{4}{x+2}\)đk : x khác -2 ; 5
\(\Rightarrow3x+6=-4x+20\Leftrightarrow7x=14\Leftrightarrow x=2\left(tmđk\right)\)
All giúp mk với
\(A=\dfrac{1}{1.2}+\dfrac{1}{2.3}+...+\dfrac{1}{49.50}\)
\(=\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{49}-\dfrac{1}{50}\)
\(=1-\dfrac{1}{50}\)
\(=\dfrac{49}{50}\)
\(A=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{49}-\dfrac{1}{50}\)
\(=1-\dfrac{1}{50}=\dfrac{49}{50}\)
giúp bài 2
Bài 5:
a: ĐKXD: n<>2
b: Khi n=0 thì A=3/2
Khi n=2 thì A=3/4
Khi n=-7 thì A=3/-5=-3/5
c: Để A là số nguyên thì \(n+2\in\left\{1;-1;3;-3\right\}\)
hay \(n\in\left\{-1;-3;1;-5\right\}\)
-10/16+(-3)/(-4)+15/24+1007/2004+(-27)/36
-10/16+(-3)/(-4)+15/24+1007/2004+(-27)/36
=-10/16+3/4+15/24+1007/2004+(-27)/36
=(-10/16+15/24) + (3/4+27/36) + 1007/2004
= 0 + 3/2 + 1007/2004
= 4013/2004
Rút gọn:
a, A= \(3-\left|3-x\right|\)
b, B= \(\left|x-6\right|+\left|6-x\right|-2\)
c, C= \(\left|-x-1\right|+\left|-x-5\right|-x\)