Question

直接寫出得數(shù)．

1 5 + 4 5 =	3 4 - 1 4 =	2 5 ×2=	3 7 × 1 3 =
5 9 × 3 5 =	1 9 ÷4=	3 5 ÷ 1 5 =	12× 3 4 =
21 25 ÷42=	1 52 × 2 3 =	1 7 ×14=	4 11 ÷4=

Answer 1

分析：分母相同的分?jǐn)?shù)相加減，分母不變，分子直接相加減；分?jǐn)?shù)相乘，先約分，然后分子、分母直接相乘．分?jǐn)?shù)除以一個(gè)整數(shù)等于這個(gè)數(shù)的倒數(shù)．

解答：解：

1 5 + 4 5 =1	3 4 - 1 4 = 1 2	2 5 ×2= 4 5	3 7 × 1 3 = 1 7
5 9 × 3 5 = 1 3	1 9 ÷4= 1 36	3 5 ÷ 1 5 =3	12× 3 4 =9
21 25 ÷42= 1 50	1 52 × 2 3 = 1 78	1 7 ×14=2	4 11 ÷4= 1 11

點(diǎn)評：此題考查了分?jǐn)?shù)的加、減、乘、除法．靈活運(yùn)用約分化簡是計(jì)算簡單化．