square root simplify by combining like terms

[dkarolasz]

sqrt(63) - 2sqrt(28) + 5sqrt(7)

I got

3sqrt(7) - 2sqrt(7) + 1 (5)sqrt(7)

3-2+5 = 6sqrt7

 

[jwpaine]

sqrt(63) - 2sqrt(28) + 5sqrt(7)

=[ 3sqrt(7) - 4sqrt(7) ] + 5sqrt(7)

=-1sqrt(7) + 5sqrt(7)

=4sqrt(7)





2sqrt(28) = 4sqrt(7) this is where you made a fatal mistake.

 

[Denis]

sqrt(63) - 2sqrt(28) + 5sqrt(7)
I got
3sqrt(7) - 2sqrt(7) + 1 (5)sqrt(7)

2nd term should be 4sqrt(7)