Question

Tìm x

a/\(\sqrt{x^2-6x+9}=\sqrt{4+2\sqrt{3}}\)

b/\(\sqrt{9x^2}=x-1\)

Answer 1

`a)\sqrt{x^2-6x+9}=\sqrt{4+2\sqrt{3}}`

`<=>\sqrt{(x-3)^2}=\sqrt{(\sqrt{3}+1)^2}`

`<=>|x-3|=\sqrt{3}+1`

`<=>[(x-3=\sqrt{3}+1),(x-3=-\sqrt{3}-1):}<=>[(x=\sqrt{3}+4),(x=-\sqrt{3}+2):}`

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`b)\sqrt{9x^2}=x-1`          `ĐK: x >= 1`

`<=>|3x|=x-1`

`<=>[(3x=x-1),(3x=1-x):}<=>[(x=-1/2),(x=1/4):}`  (ko t/m)

  `=>` Ptr vô nghiệm