Toán Lớp 8: a)a)tìm x,biết:(2x-5)^2-x^2=0
b)thực hiện phép tính $\frac{x-4}{x^2-2x}$+$\frac{1}{x-2}$- $\frac{1}{x}$
Leave a reply
Register Now
Login
Lost Password
Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Toán Lớp 8: a)a)tìm x,biết:(2x-5)^2-x^2=0
b)thực hiện phép tính $\frac{x-4}{x^2-2x}$+$\frac{1}{x-2}$- $\frac{1}{x}$
Comments ( 2 )
(2x-5)^2-x^2=0
<=>(2x-5-x)(2x-5+x)=0
<=>(x-5)(3x-5)=0
<=>[(x-5=0),(3x-5=0):}
<=>[(x=5),(3x=5):}
<=>[(x=5),(x=5/3):}
Vậy x\in{5;5/3}
b)
(x-4)/(x^2-2x)+1/(x-2)-1/x(x\ne0;2)
=(x-4)/(x.(x-2))+x/(x.(x-2))-(x-2)/(x.(x-2))
=(x-4+x-x+2)/(x.(x-2))
=(x-2)/(x.(x-2))
=1/x