please help solving a sqrt root using division

Question

 

would you please help me simplify and solve

 

 

√18÷√8 - 3

 

I started with √18 · √18 + 3

                     ___________

                    √18 - 3 · √18 + 3

 

then got √(18)(8) + 3√18

                              _____

                               8-9

 

then √144 + 3√18

                   _____

                    -1

Answer 1

√(18) ÷ √(8) - 3 =

 

√(18/8) - 3 =

 

√(9/4) - 3 =

 

3/2 - 3 =

 

3/2 - 6/2 =

 

- 3/2

Answer 2

L,

 

I don't know how to interpret what you've written.  Is it

 

(√18/√8) -3 or √18/√(8 - 3)?

 

The first interpretation gives -(3/2)

 

The second interpretation gives √18/√5 gives [(3√10)/5]

 

In either case, don't think of 18 as being 18: think of it as 2*3*3 or (2)*(3)²

 

So √(18) can be replaced with 3*√2

 

and 

 

Similarly, don't think of 8 as being 8: think of it as 2*2*2 or 2*(2)²

 

So that √(8) becomes 2*√2

 

So that √(18)/√(8) = (3*√2)/(2*√2) = 3/2

 

and 3/2 - 3 = -3/2

Answer 3

 √18 / √8  -3  =

 

  3√2 - 3  =

  2√2

 

   3  -  3 = -3

   2            2

 

 

  Division of irrational numbers are the same as rationalization of denominator, always have to use fractions.