2/5+1/2×3/5+7/10;12/13×3/7+4/7 用简便方法计算
人气:360 ℃ 时间:2020-05-20 19:05:26
解答
2/5+1/2×3/5+7/10
=2/5+3/10+7/10
=2/5+1
=7/5
12/13×3/7+4/7
=(9/13+1)×4/7
=22/13×4/7
=88/91=(9/13+1)×4/7 =22/13×4/7=88/91 9/13是怎样出来的?12/13×3/7+4/7 =3×4/13×3/7+4/7 =3×3/13×4/7+4/7 =(9/13+1)×4/7 =22/13×4/7=88/91还是不明白啊,3×3/13×4/7+4/7怎么做的?12/13×3/7+4/7 =3×4/13×3/7+4/7 =3×3/13×4/7+4/7 =9/13×4/7+4/7 提取公因数4/7=(9/13+1)×4/7 =22/13×4/7=88/91=3×3/13×4/7+4/7 中3/13×4/7怎样出来的?我愚笨还是不明白,请详细说明12/13×3/7+4/7 =3×4/13×3/7+4/7 =(3×3×4)/(13×7)+4/7 (乘法交换律,分子交换)=(9×4)/(13×7)+4/7 =9/13×4/7+4/7
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