Toán Lớp 6: Tìm ƯCLN và BCNN của các số sau a) 12; 15; 18 b) 24; 36; 150 c) 72; 108; 150 d) 45; 60; 105 :)

Question

Toán Lớp 6:  Tìm ƯCLN và BCNN của các số sau a) 12; 15; 18 b) 24; 36; 150 c) 72; 108; 150 d) 45; 60; 105 :)

thanoanghha · Answer

Giải đáp:       Lời giải và giải thích chi tiết:    $a,$   $Ta$ $c&oacute;:$   $12=2^{2}.3$   $15=3.5$   $18=2.3^{2}$   $=>ƯCLN(12,15,18)=3$        $BCLN(12,15,18)=2^{2}.3^{2}.5=4.9.5=180$   $b,$   $Ta$ $c&oacute;:$   $24=2^{3}.3$   $36=2^{2}.3^{2}$   $150=2.3.5^{2}$   $=>ƯCLN(24,36,150)=2.3=6$        $BCNN(24,36,150)=2^{3}.3^{2}.5^{2}=8.9.25=1800$   $c,$   $Ta$ $c&oacute;:$   $72=2^{3}.3^{2}$   $108=2^{2}.3^{3}$   $150=2.3.5^{2}$   $=>ƯCLN(72,108,150)=2.3=6$        $BCNN(72,108,150)=2^{3}.3^{3}.5^{2}=5400$   $d,$   $Ta$ $c&oacute;:$   $45=3^{2}.5$   $60=2^{2}.3.5$   $105=3.5.7$   $=>ƯCLN(45,60,105)=5$        $BCNN(45,60,105)=2^{2}.3^{2}.5.7=4.9.5.7=1260$   (B&agrave;i tham khảo)

lanminhngoc · Answer

a) Ta c&oacute; :   12=2^2 .3   15=3.5   18=3^2 .2   => text{ƯCLN}_{(12,15,18)}=3           text{BCNN}_{(12,15,18)}=2^2 .3^2 .5=180   b) Ta c&oacute; :   24=2^3 .3   36=2^2 .3^2   150=2.3.5^2   => text{ƯCLN}_{(24,36,150)}=2.3=6           text{BCNN}_{(24,36,150)}=2^3 .3^2 .5^2=1800   c) Ta c&oacute; :   72=2^3 .3^2   108=2^2 .3^3   150=2.3.5^2   => text{ƯCLN}_{(72,108,150)}=2.3=6           text{BCNN}_{(72,10,150)}=2^3 .3^3 .5^2=5400   d) Ta c&oacute; :   45=3^2 .5   60=2^2 .3.5   105=3.5.7   => text{ƯCLN}_{(45,60,105)}=3.5=15           text{BCNN}_{(45,60,105)}=2^2 .3^2 .5.7=1260