Toán Lớp 5: tính nhanh
1.3×4+4×6+9×2+18
2.2×5+5×7+9×3.Giúp mình với
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Toán Lớp 5: tính nhanh
1.3×4+4×6+9×2+18
2.2×5+5×7+9×3.Giúp mình với
Comments ( 2 )
1.3xx4+4xx6+9xx2+18
= 4xx(3+6)+9xx2+18
=4xx9+9xx2+18
=9xx(4+2)+18
=9xx6+18=54+18=72
2.2xx5+5xx7+9xx3
= 5xx(2+7)+9xx3
= 5xx9+9xx3
=9xx(5+3)
=8xx9=72
1. 3xx4 + 4xx6 + 9xx2 + 18
= 4.(3 + 6) + 9.2 + 9.2
= 4.9 + 9.2 + 9.2
= 9.(4 + 2 + 2)
= 9.8
= 72
2. 2xx5 + 5xx7 + 9xx3
= 5.(2 +7) + 9.3
= 5.9 + 9.3
= 9.(5 + 3)
= 9.8
= 72