-8*sqrt(7) -3*sqrt(2)+4*sqrt(28) -sqrt(147)
28=4*7=2^2*7 & 147=3*49=3*7^2
so yu hav -3*sqrt(2) -8*sqrt(7) +4*2*sqrt(7) -7*sqrt(3)
or -3*sqrt(2) -7*sqrt(3) +(4*2 -8)*sqrt(7)
=-3sqrt(2) -7sqrt(3)
sqrt(2)=1.41421 35623 73095 04880 16887 24209 69807 8569...
sqrt(3)=1.73205 08075 68877 29352 74463 41505 87236 69...