Question 73293
{{{(10+sqrt(20))-(4-sqrt(45))}}}Start with given problem
{{{(10+sqrt(4*5))-(4-sqrt(9*5))}}}Display radicand as product
{{{(10+sqrt(4)*sqrt(5))-(4-sqrt(9)*sqrt(5))}}}Break up square root
{{{(10+2*sqrt(5))-(4-3*sqrt(5))}}}Take square root of perfect square
{{{10+2*sqrt(5)-4+3*sqrt(5))}}}Distribute negative
{{{10-4+2*sqrt(5)+3*sqrt(5))}}}Group like terms
{{{6+sqrt(5)(2+3)}}}Group {{{sqrt(5)}}} terms together (note: {{{sqrt(5)}}} is like x. ie 3x+2x=x(3+2))
{{{6+5*sqrt(5)}}}This is what you should get
Hope this makes sense.