1so sánh
a)\(\sqrt{3}+1v\text{à}\sqrt{2+2}\)
b)\(\sqrt{3}+\sqrt{5}-1v\text{à}\sqrt{6}-\sqrt{2}+3\)
2)tìm đk đêr căn có nghiã
a)\(\sqrt{3x-7}\)
b)\(\sqrt{2-5x}\)
c)\(\sqrt{\dfrac{-3}{x-5}}\)
d)\(\sqrt{5x^2-x-4}\)
e)\(\sqrt{9-x^2}\)
...
Đọc tiếp
1so sánh
a)\(\sqrt{3}+1v\text{à}\sqrt{2+2}\)
b)\(\sqrt{3}+\sqrt{5}-1v\text{à}\sqrt{6}-\sqrt{2}+3\)
2)tìm đk đêr căn có nghiã
a)\(\sqrt{3x-7}\)
b)\(\sqrt{2-5x}\)
c)\(\sqrt{\dfrac{-3}{x-5}}\)
d)\(\sqrt{5x^2-x-4}\)
e)\(\sqrt{9-x^2}\)
f)\(\sqrt{x^2-1}\)
Bài 2:
a: ĐKXĐ: 3x-7>=0
hay x>=7/3
b: ĐKXĐ: \(2-5x\ge0\)
hay x<=2/5
c: ĐKXĐ: \(\dfrac{-3}{x-5}\ge0\)
=>x-5<0
hay x<5
d: ĐKXĐ: \(5x^2-x-4\ge0\)
\(\Leftrightarrow5x^2-5x+4x-4\ge0\)
\(\Leftrightarrow\left(x-1\right)\left(5x+4\right)\ge0\)
=>x>=1 hoặc x<=-4/5
e: ĐKXĐ: \(9-x^2\ge0\)
\(\Leftrightarrow\left(x-3\right)\left(x+3\right)\le0\)
=>-3<=x<=3
f: ĐKXĐ: \(x^2-1\ge0\)
=>(x-1)(x+1)>=0
=>x>=1 hoặc x<=-1