34乘72加34乘2=34×（72+2）=34×74=2516
34×72+34×2=34×（72+2）=34×（70+4）=34×70+34×4=238+136=374
34x72+34x2=34x(72+2)=34x74=2516
34×72+34×2=34×(72+2)=34×74=2516
37×（72+2）=37×74=2738
34*(72+2)
