mutiplying and adding radicals

Simplify the following:
sqrt(50)-2 sqrt(72)+3 sqrt(18)

sqrt(72)  =  sqrt(2^3×3^2)  =  2×3 sqrt(2):
sqrt(50)-2×2×3 sqrt(2)+3 sqrt(18)

2×3  =  6:
sqrt(50)-2×6 sqrt(2)+3 sqrt(18)

sqrt(18)  =  sqrt(2×3^2)  =  3 sqrt(2):
sqrt(50)-2×6 sqrt(2)+3×3 sqrt(2)

sqrt(50)  =  sqrt(2×5^2)  =  5 sqrt(2):
5 sqrt(2)-2×6 sqrt(2)+3×3 sqrt(2)

-2×6  =  -12:
5 sqrt(2)+-12 sqrt(2)+3×3 sqrt(2)

3×3  =  9:
5 sqrt(2)-12 sqrt(2)+9 sqrt(2)

Add like terms. 5 sqrt(2)-12 sqrt(2)+9 sqrt(2)  =  2 sqrt(2):
Answer: |  2 sqrt(2)
 

2sqrt(2)

sqrt(50)-2sqrt(72)+3(sqrt(18)  =

sqrt(25 * 2)  - 2sqrt(36 * 2) + 3sqrt(9 *2)  =

5 sqrt(2) - 6 * 2 sqrt(2) + 3*3 sqrt(2) =

5 sqrt(2) - 12 sqrt(2) + 9 sqrt(2) =

[ 5 - 12 + 9]sqrt(2) =

2sqrt(2)

sqrt(50)-2sqrt(72)+3(sqrt(18)) = ?

$\begin{array}{rcll} \sqrt{50}-2\sqrt{72}+3\sqrt{18} &=& \sqrt{50}-2\sqrt{4\cdot18}+3\sqrt{18}\\ &=& \sqrt{50}-2\cdot2\sqrt{18}+3\sqrt{18}\\ &=& \sqrt{50}-4\sqrt{18}+3\sqrt{18}\\ &=& \sqrt{50}-\sqrt{18}\\ &=& \sqrt{2\cdot5^2}-\sqrt{2\cdot3^2}\\ &=& 5\sqrt{2}-3\sqrt{2}\\ &=& 2\sqrt{2}\\ \end{array}$