1) ab^3-ab3+ab-3a
2) 16^8=(4^2)^8=4^16-4^1=4^15
3) 2s(3ab)/2s(a+2b)=3ab/a+2b
4) (3x-6)(x+3)=x^2+4
x^2+4=0
x=+/-2
5) (67+33+71/2)24+29+1c
