a).50%+7/12-1/2 b).2014×65+2014×45-2014×10 c).125-25:3×12 d).(2013×2014+2014×2015+2015×2016)x(1+1/3-một một phần ba) e).17,75+16,25+14,75+13,25……+4,25+2,75+1,25
a).50%+7/12-1/2 b).2014×65+2014×45-2014×10 c).125-25:3×12 d).(2013×2014+2014×2015+2015×2016)x(1+1/3-một một phần ba) e).17,75+16,25+14,75+13,25……+4,25+2,75+1,25
a)50% + 7/12 – 1/2
= 1/2 + 7/12 – 1/2
= (1/2 – 1/2) + 7/12
= 0 + 7/12
= 7/12
b)2014 × 65 + 2014 × 45-2014×10
= 2014×(65 + 45 -10)
= 2014 × (110 – 10)
=2014 × 100=201400
c)125 – 25 : 3 × 12
= 125 – 25 × 12 : 3
= 125 – 300 : 3
= 125 – 100
= 25
d)(2013 × 2014 + 2014 × 2015 + 2015 × 2016) × (1 + 1/3 – 1 1/3)
=(2013 × 2014 + 2014 × 2015 + 2015 × 2016) × (1 1/3 – 1 1/3)
=(2013 × 2014 + 2014 × 2015 + 2015 × 2016) × 0
= 0
e)17,75 + 16,25 + 14,75 + 13,25 +….+ 4,25 + 2,75 + 1,25
=(17,75 + 1,25) + (16,25 + 2,75) + (14,75 + 4,25) + ….+ (10,75 + 8,25)
Tổng số các số hạng ở tổng trên là:
(17,75 – 1,25): 1,5 +1=12(số hạng)
Tổng trên có: 12 : 6 =6 cặp
Mà mỗi cặp = 19
⇔ tổng trên= 19 × 6=114
`a)“50%+7/12-1/2`
`= 1/2 + 7/12 – 1/2`
`= 7/12`
`b)“2014 \times 65+2014 \times 45-2014 \times 10`
`= 2014 \times (65 + 45 – 10)`
`=2014 \times 100`
`= 201400`
`c)“125-25:3 \times 12`
`= 125 – 25 \times 1/3 \times 12`
`= 125 – 100`
`=25`
`d)“(2013\times 2014+2014 \times 2015+2015 \times 2016) \times (1 + 1/3- 1\frac{1}{3})`
`=(2013\times 2014+2014 \times 2015+2015 \times 2016) \times 0`
`=0`
`e)“17,75+16,25+14,75+13,25……+4,25+2,75+1,25`
`= \frac{(17,75+1,25).[(17,75-1,25):1,5 +1]}{2}`
`= \frac{19.12}{2}`
`=114`.