Đáp án :
`A = 35`
`B = \frac{-3+\sqrt3}{3}`
Giải thích các bước giải :
`A= ( \sqrt5 - 3\sqrt20 + 4\sqrt45 ) . \sqrt5`
`A= ( \sqrt5 - 3 \sqrt4.5 + 4\sqrt9.5 ) . \sqrt5`
`A= ( \sqrt5 - 3.2\sqrt5 + 4.3\sqrt5 ) . \sqrt5`
`A= ( \sqrt5 - 6\sqrt5 + 12\sqrt5 ) . \sqrt5`
`A= 7\sqrt5 . \sqrt5`
`A= 35`
`--------------`
`B = \sqrt{4-2\sqrt3} - \frac{3+2\sqrt3}{2+\sqrt3} + \sqrt{frac{1}{3} `
`B = \sqrt{3-2\sqrt3 +1 } - \frac{\sqrt3 ( \sqrt3+2) }{2 + \sqrt3}+\sqrt{frac{1}{3}`
`B = \sqrt{(\sqrt3 - 1)^2 }- \sqrt3 + \sqrtfrac{1}{3}`
`B = | \sqrt3 - 1 | - \sqrt3 + \sqrtfrac{1}{3}`
`B = -1 + \sqrt3 - \sqrt3 + \sqrtfrac{1}{3}`
`B = -1 + \frac{\sqrt3}{3}`
`B = \frac{-3 + \sqrt3}{3}`
