Bài 1
1. Giải phương trình :
View attachment 143932
[tex]<=> 7.(\sqrt{x-4}-1)+3.(x-5)-14.(\sqrt{x+4}-3)=0\\\\ <=> \frac{7.(x-5)}{\sqrt{x-4}+1}+3.(x-5)-\frac{14.(x-5)}{\sqrt{x+4}+3}=0\\\\ <=> (x-5).(\frac{7}{\sqrt{x-4}+1}+3-\frac{14}{\sqrt{x+4}+3})=0\\\\ *, x-5=0 <=>...\\\\ *, \frac{7}{\sqrt{x-4}+1}+3-\frac{14}{\sqrt{x+4}+3}=0 (1)\\\\ +, 0<\sqrt{x-4}+1<\sqrt{x+4}+3\\\\ => \frac{7}{\sqrt{x-4}+1}>\frac{7}{\sqrt{x+4}+3}\\\\ +, \sqrt{x+4}>0 => \sqrt{x+4}+3>3 => \frac{-7}{\sqrt{x+4}+3}>\frac{-7}{3}\\\\ => 3-\frac{7}{\sqrt{x+4}+3}>0\\\\ => (1) vô nghiệm[/tex]
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