a) 20,22×96+20,22:0,25
b) 202,3×91+202,3:0,125+202,3
c) 1/6+1/12+1/20+1/30+1/42+1/50+1/72
d) 3×4×36+6×2×64
2 câu trả lời
$\text{a) 20,22 × 96 + 20,22 : 0,25 }$
$\text{= 20,22 × 96 + 20,22 × 4 }$
$\text{= 20,22 × ( 96 + 4 ) }$
$\text{= 20,22 × 100 }$
$\text{= 2022 }$
$\text{b) 202,3 × 91 + 202,3 : 0,125 + 202,3}$
$\text{= 202,3 × 91 + 202,3 × 8 + 202,3 × 1}$
$\text{= 202,3 × ( 91 + 8 + 1 ) }$
$\text{= 202,3 × 100}$
$\text{= 20230}$
c) `1/6` + `1/12` + `1/20` + `1/30` + `1/42` + `1/56` + `1/72`
= `1/(2.3)` + `1/(3.4)` + ....... + `1/(8.9)`
= `1/2` - `1/3` + `1/3` - `1/4` + ..... + `1/8` - `1/9`
= `1/2` - `1/9`
= `9/18` - `2/18`
=`7/18`
$\text{d) 3 × 4 × 36 + 6 × 2 × 64}$
$\text{= 12 × 36 +12 × 64}$
$\text{= 12 × ( 36 + 64 ) }$
$\text{= 12 × 100}$
$\text{= 1200 }$
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