1)
a)
`5\sqrt10+\sqrt1000+\sqrt10`
`=5\sqrt10+\sqrt{100.10}+\sqrt10`
`=5\sqrt10+10\sqrt10+\sqrt10`
`=16\sqrt10`
b)
`5\sqrt13+\sqrt48-\sqrt78+\sqrt8`
`=5\sqrt13+\sqrt(16.3)-\sqrt78+\sqrt(4.2)`
`=5\sqrt13+4\sqrt3-\sqrt78+2\sqrt2`
c)
`\sqrt{16xy^2}` với `x>=0;y>=0`
`=\sqrt{4^(2)xy^2}`
`=4y\sqrtx`
d)
`\sqrt{27z^2k}` với `k>=0;z<0`
`=\sqrt{9.3z^2k}`
`=-3z\sqrt{3k}`
