Nguyễn T.Phương Anh
Giới thiệu về bản thân
b)ta có Q=4
<=>\(\dfrac{\sqrt{a}+1}{\sqrt{a}}\) =4 <->\(\sqrt{a}+1=4.\sqrt{a}\)
<->\(\sqrt{a}+1=4\sqrt{a}\)
<->-3\(\sqrt{a}\) =1<=>\(\sqrt{a}\) =\(\dfrac{-1}{3}\)
<-> a=1/9
vậy ..........
a)Q=\(\dfrac{1}{\sqrt{a}+1}-\dfrac{1}{a+\sqrt{a}}:\dfrac{\sqrt{a}-1}{a+2\sqrt{a}+1}\left(a>0\right)\)
Q=\(\dfrac{1}{\sqrt{a}+1}-\dfrac{1}{\sqrt{a}\left(\sqrt{a}+1\right)}:\dfrac{\sqrt{a}-1}{\left(\sqrt{a}+1\right)^2}\)
Q= \(\dfrac{\sqrt{a}-1}{\sqrt{a}\left(\sqrt{a}+1\right)}.\dfrac{\left(\sqrt{a}+1\right)^2}{\sqrt{a}-1}\) =\(\dfrac{\sqrt{a}+1}{\sqrt{a}}\)
vậy...
b. so sánh
\(\sqrt{17}-3\sqrt{32}+\sqrt{17}-3\sqrt{32}\)
=(\(\sqrt{17}+\sqrt{17}\) )+(-3\(\sqrt{32}-3\sqrt{32}\) )
=-6\(\sqrt{32}\)
vậy ....
500-(5x+70)=\(5^2\).4
500-(5x+70)=25.4
500-(5x+70)=100
5x+70=500-100
5x+70=400
5x=400-70
5x=330
x=330:5
x=66
vậy.....
mênh mông :))