The key to Jay-Z’s mainstream appeal is that he often pairs darkly credible street tales with sunny pop hooks. On his new single, he muses about the drug game and comments on his upcoming assault trial (”not guilty/Y’all got to feel me”) over a snatch of the Jackson 5’s effervescent ”I Want You Back.” Thoroughly uninventive, the peppy, tough-minded tune nonetheless proves there’s some zip left in the rapper’s familiar formula.