`a, sqrt(7x^2) = xsqrt 7`
`b, sqrt(8y^2) = -2y sqrt 2`
`c, 2 sqrt(25x^3) = 2 . 5 |x| sqrt(x) = 10 |x| sqrt x`
`d, sqrt(48y^4) = 4y^2 sqrt(3)`.
a: \(=x\sqrt{7}\)
b: \(=-2\sqrt{2}y\)
c: \(=2\cdot5\cdot x\sqrt{x}=10x\sqrt{x}\)
d: \(=4\sqrt{3}\cdot y^2\)