1. a,b,c,d均不为0,如果$\frac{b}{a}×\frac{d}{c}= \frac{b}{a}$,那么(
A.c>d
B.c<d
C.c= d
D.三种都可能
C
)。A.c>d
B.c<d
C.c= d
D.三种都可能
答案:
C
2. a,b,c,d均不为0,那么$\frac{b}{a}×\frac{d}{c}=$(
A.$\frac{b× d}{a}$
B.$\frac{b}{a× c}$
C.$\frac{b× d}{a× c}$
D.$\frac{b× d}{c}$
C
)。A.$\frac{b× d}{a}$
B.$\frac{b}{a× c}$
C.$\frac{b× d}{a× c}$
D.$\frac{b× d}{c}$
答案:
C
3. 如果$\frac{5}{a}×\frac{6}{b}= 1$,那么(
A.a= 30
B.b= 30
C.ab= 1
D.ab= 30
D
)。A.a= 30
B.b= 30
C.ab= 1
D.ab= 30
答案:
D
4. $\frac{5}{8}×\frac{a}{5}= \frac{1}{4}$,a等于(
A.1
B.2
C.4
D.5
B
)。A.1
B.2
C.4
D.5
答案:
B
1. 直接写得数。
$\frac{1}{2}-\frac{1}{3}=$
$\frac{2}{3}×\frac{2}{3}=$
$\frac{2}{3}+\frac{3}{4}=$
$\frac{1}{2}-\frac{1}{3}=$
$\frac{1}{6}$
$\frac{1}{6}+\frac{1}{3}=$$\frac{1}{2}$
$\frac{3}{8}×16=$6
$\frac{4}{7}×\frac{1}{4}=$$\frac{1}{7}$
$\frac{2}{3}×\frac{2}{3}=$
$\frac{4}{9}$
$\frac{3}{4}×\frac{8}{9}=$$\frac{2}{3}$
$\frac{7}{10}×16=$$\frac{56}{5}$
$\frac{5}{6}×\frac{3}{10}=$$\frac{1}{4}$
$\frac{2}{3}+\frac{3}{4}=$
$\frac{17}{12}$
$\frac{1}{6}-\frac{1}{7}=$$\frac{1}{42}$
$\frac{2}{3}×6=$4
$\frac{2}{9}×\frac{1}{2}=$$\frac{1}{9}$
答案:
$\frac{1}{6}$;$\frac{1}{2}$;6;$\frac{1}{7}$;$\frac{4}{9}$;$\frac{2}{3}$;$\frac{56}{5}$;$\frac{1}{4}$;$\frac{17}{12}$;$\frac{1}{42}$;4;$\frac{1}{9}$
2. 计算。
$\frac{14}{65}×\frac{26}{21}$ $\frac{34}{33}×\frac{22}{17}$ $0×\frac{8}{15}×\frac{3}{2}$
$\frac{10}{21}×\frac{12}{25}$ $\frac{12}{19}×\frac{11}{24}$ $\frac{2}{5}×21×\frac{15}{14}$
$\frac{14}{65}×\frac{26}{21}$ $\frac{34}{33}×\frac{22}{17}$ $0×\frac{8}{15}×\frac{3}{2}$
$\frac{10}{21}×\frac{12}{25}$ $\frac{12}{19}×\frac{11}{24}$ $\frac{2}{5}×21×\frac{15}{14}$
答案:
$\frac{14}{65}×\frac{26}{21}=\frac{14×26}{65×21}=\frac{2×2}{5×3}=\frac{4}{15}$
$\frac{34}{33}×\frac{22}{17}=\frac{34×22}{33×17}=\frac{2×2}{3×1}=\frac{4}{3}$
$0×\frac{8}{15}×\frac{3}{2}=0$
$\frac{10}{21}×\frac{12}{25}=\frac{10×12}{21×25}=\frac{2×4}{7×5}=\frac{8}{35}$
$\frac{12}{19}×\frac{11}{24}=\frac{12×11}{19×24}=\frac{1×11}{19×2}=\frac{11}{38}$
$\frac{2}{5}×21×\frac{15}{14}=\frac{2×21×15}{5×14}=\frac{2×3×3}{1×2}=9$
$\frac{34}{33}×\frac{22}{17}=\frac{34×22}{33×17}=\frac{2×2}{3×1}=\frac{4}{3}$
$0×\frac{8}{15}×\frac{3}{2}=0$
$\frac{10}{21}×\frac{12}{25}=\frac{10×12}{21×25}=\frac{2×4}{7×5}=\frac{8}{35}$
$\frac{12}{19}×\frac{11}{24}=\frac{12×11}{19×24}=\frac{1×11}{19×2}=\frac{11}{38}$
$\frac{2}{5}×21×\frac{15}{14}=\frac{2×21×15}{5×14}=\frac{2×3×3}{1×2}=9$
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