Thực hiện các phép tính sau

Đáp án+Giải thích các bước giải:

c,

`\sqrt(7-2\sqrt10)-\sqrt(7+2\sqrt10)`

`=\sqrt(5-2\sqrt10+2)-\sqrt(5+2\sqrt10+2)`

`=\sqrt(\sqrt5^2-2\sqrt5. \sqrt2+\sqrt2^2)-\sqrt(\sqrt5^2+2\sqrt5. \sqrt2+\sqrt2^2)`

`=\sqrt((\sqrt5-\sqrt2)^2) -\sqrt((\sqrt5+\sqrt2)^2)`

`=|\sqrt5-\sqrt2|-|\sqrt5+\sqrt2|`

`=(\sqrt5-\sqrt2)-(\sqrt5+\sqrt2)`

`=\sqrt5-\sqrt2-\sqrt5-\sqrt2`

`=-2\sqrt2`

d,

`\sqrt(6+2\sqrt5)-\sqrt(6-2\sqrt5)`

`=\sqrt(5+2\sqrt5+1)-\sqrt(5-2\sqrt5+1)`

`=\sqrt(\sqrt5^2+2\sqrt5.1+1^2)-\sqrt(\sqrt5^2-2\sqrt5.1+1^2)`

`=\sqrt((\sqrt5+1)^2)-\sqrt((\sqrt5-1)^2)`

`=|\sqrt5+1|-|\sqrt5-1|`

`=(\sqrt5+1)-(\sqrt5-1)`

`=\sqrt5+1-\sqrt5+1`

`=2`