Question

B=\(\dfrac{1}{x}\)+\(\dfrac{1}{x+5}\)+\(\dfrac{x-5}{x\left(x+5\right)}\)

1) rút gọn B.

2) tìm x để B > 0 .

3) tìm x sao cho B nhận giá trị nguyên.

Answer 1

 

 

 

 

a)B=x+5 +x +x-5/x(x-5)=3x/x(x-5)=3/x-5

        b)đkxđ   x khác 5

Answer 2

 

a)B=x+5 +x +x-5/x(x-5)=3x/x(x-5)=3/x-5

        b)đkxđ   x khác 5

Answer 3

1, đk x khác 0 ; -5 

\(B=\dfrac{x+5+x+x-5}{x\left(x+5\right)}=\dfrac{3}{x+5}\)

2, B = 3/(x+5) > 0 => x + 5 > 0 <=> x > -5 

3, \(\Rightarrow x+5\inƯ\left(3\right)=\left\{\pm1;\pm3\right\}\)

x + 5	1	-1	3	-3
x	-4	-6	-2	-8