1) √5a - 3√20a + √125a =√5a - 3√(45)a + √(255)a =√5a - 6√5a + 5√5a =0
2) (3√2 + 2√7)(√2 - √56) =3√2√2 - 3√2√56 + 2√7√2 - 2√7√56 =6 - 84√2 + 2√14 - 4√14 =10 - 84√2 - 2√14
3) (√7 -3)(3 + √7) =3√7 + 7 - 9 - 3√7 =-2
1) √5a - 3√20a + √125a =
√5a - 3√(45)a + √(255)a =
√5a - 6√5a + 5√5a =
0
2) (3√2 + 2√7)(√2 - √56) =
3√2√2 - 3√2√56 + 2√7√2 - 2√7√56 =
6 - 84√2 + 2√14 - 4√14 =
10 - 84√2 - 2√14
3) (√7 -3)(3 + √7) =
3√7 + 7 - 9 - 3√7 =
-2