3u^2+8u-3 with grouping, we have to find 2 numbers which add up to 8 and multiply to 3*(-3)= -9. testing, we find that 9 and -1 add up to 8 and multiply to -9. so now we can write the original equation as 3u^2-u+9u-3 you can factor the terms in pairs: u(3u-1)+3(3u-1)= (u+3)(3u-1)
