Tính căn2 +căn3 +căn50 Tính 2/1-căn3 - 2/1+căn3 Giải pt Căn(x-3)2 =9 Căn2x khác5 =7

a) `\sqrt{2}+\sqrt{3}+\sqrt{50}`

`=\sqrt{2}+\sqrt{3}+5\sqrt{2}`

`=6\sqrt{2}+\sqrt{3}`

b) `2/(1-\sqrt{3})-2/(1+\sqrt{3})`

`=(2(1+\sqrt{3}))/((1-\sqrt{3})(1+\sqrt{3}))-(2(1-\sqrt{3}))/((1+\sqrt{3})(1-\sqrt{3}))`

`=(2(1+\sqrt{3}))/(-2)-(2(1-\sqrt{3}))/(-2)`

`=-1-\sqrt{3}+1-\sqrt{3}`

`=-2\sqrt{3}`

c) `\sqrt{(x-3)^2}=9` `(x∈R)`

⇔`|x-3|=9`

⇔\(\left[ \begin{array}{l}x-3=9\\x-3=-9\end{array} \right.\) 

⇔\(\left[ \begin{array}{l}x=12(tm)\\x=-6(tm)\end{array} \right.\) 

Vậy `S={12,-6}`

Đáp án:

Giải thích các bước giải:

`a)\sqrt{2}+\sqrt{3}+\sqrt{50}=\sqrt{2}+\sqrt{3}+5\sqrt{2}=6\sqrt{2}+\sqrt{3}`$\\$ `b)2/(1-\sqrt{3})-2/(1+\sqrt{3})=(2(1+\sqrt{3}))/((1-\sqrt{3})(1+\sqrt{3}))-(2(1-\sqrt{3}))/((1+\sqrt{3})(1-\sqrt{3}))`$\\$`=(2(1+\sqrt{3}))/(-2)-(2(1-\sqrt{3}))/(-2)=-1-\sqrt{3}+1-\sqrt{3}=-2\sqrt{3}`$\\$`c)\sqrt{(x-3)^2}=9<=>|x-3|=9`$\\$`<=> x-3=9\text{ hoặc }x-3=-9`$\\$`<=> x=12(tm)\text{ hoặc }x=-6(tm)`$\\$`\text{Vậy ...}`