Toán Lớp 5: tính nhanh 15x48x3/6x5x3 4x3x6/20x12x21 50x24x42/7x8x10
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Toán Lớp 5: tính nhanh 15x48x3/6x5x3 4x3x6/20x12x21 50x24x42/7x8x10
Comments ( 2 )
(15 xx 48 xx 3)/(6 xx 5 xx 3)
= (5 xx 3 xx 6 xx 8 xx 3)/(6 xx 5 xx 3)
= 8 xx 3
= 24
_________________________________________
(4 xx 3 xx 6)/(20 xx 12 xx 21)
= (4 xx 3 xx 6)/(4 xx 5 xx 2 xx 6 xx 3 xx 7)
= 1/(5 xx 2 xx 7)
= 1/(10 xx 7)
= 1/70
_________________________________________
(50 xx 24 xx 42)/(7 xx 8 xx 10)
= (5 xx 10 xx 3 xx 8 xx 6 xx 7)/(7 xx 8 xx 10)
= 5 xx 3 xx 6
= 15 xx 6
= 90
Giải đáp:
$\frac{15×48×3}{6×5×3}$
=$\frac{15×48×3}{6×5×3}$
=$\frac{3×5×6×8×3}{6×5×3}$
=3 × 8
=24
$\frac{4×3×6}{20×12×21}$
= $\frac{4×3×6}{4×5×2×6×3×7}$
=$\frac{1}{5×2×7}$
=$\frac{1}{70}$
$\frac{50×24×42}{7×8×10}$
=$\frac{5×10×3×8×6×7}{7×8×10}$
=5×3×6
=15×6
=90