Question

Simplify 1)  root 45 - 3 root 20 + 4 root 5
2)  (r + root 3) (3 - root 3)
3)  4 root 28 divide by 3 root 7

Answer 1

1)√45-3√20+4√5
=√9×5-3√4×5+4√5
=3√5-6√5+4√5
=-3√5+4√5
=√5
2)(3+√3) (3-√3)
=3²-(√3)²
=9-3
=6
3)4√28/3√7
=4√7×4/3√7
=8√7/3√7
=8/3

Answer 2

1)45^1/2-3*20^1/2+4*5^1/2
  =3*5^1/2-6*5^1/2+4*5^1/2
  =5^1/2
2)(3+3^1/2)(3-3^1/2)
   =3^2-(3^1/2)^2   [(a+b)(a-b)=a^2-b^2]
   =9-3                     [(a^m)^n=a^m*n]
   =6
3)4*(28^1/2)/3*7^1/2
   =8*(7^1/2)/3*7^1/2
   =8/3