2015+2016x2017/2017x2018-2019
2015/2016+1/2016x2017+1\2017x2018
nhanh lên nha mk cần gấp lắm!
nhớ có lời giải nha. ai nhanh mk tích cho!
\(\frac{2015}{2016}\)+ \(\frac{1}{2016}\)x 2017 +\(\frac{1}{2017}\) x2018 =\(\frac{6052}{2017}\)
Tính:
\(A=\frac{1x2+2x3+3x4+...+2016x2017}{2017x2018}\)
Gọi B = 1x2 + 2 x 3 + 3 x 4 + ... + 2016 x2017
3B = 3 x ( 1x2 + 2x3 + 3x4 + ... + 2016x2017)
= 1x2x3 + 2x3x3 + 3x4x3 + ... + 2016x2017x3 )
= 1x2x3 + 2x3x( 4-1) + 3x4x( 5 -2 ) + ... + 2016x2017x( 2018 - 2015)
= 1x2x3 + 2x3x4 - 1x2x3 + 3x4x5 - 2x3x4 + ... + 2016x2017x2018 - 2015x2016x2017
= 2016 x2017 x2018
B = 672 x2017 x2018
Mà A = \(\frac{672x2017x2018}{2017x2018}\)
= 672
Vậy A = 672
\(\frac{2017x2018+1}{2019+2016x2018}\)Tính nhanh
Ta có :
\(\frac{2017\times2018+1}{2019+2016\times2018}\)
\(=\frac{2017\times2018+1}{1+2018+2016\times2018}\)
\(=\frac{2017\times2018+1}{1+2018\times\left(2016+1\right)}\)
\(=\frac{2017\times2018+1}{1+2018\times2017}\)
\(=1\)
\(\frac{2017.2018+1}{2019+2016.2018}\)
\(=\frac{2017.2018+1}{1+2018+2016.2018}\)
\(=\frac{2017.(2018+1)}{(1+2018).\left(2016+1\right)}\)
\(=\frac{2017.2019}{2019.2017}\)
\(=\frac{1}{1}=1\)
Tính hợp lý:
a,21,18x2117-2017x2018
b,(1+3+5+ .......+2019)x(432432x468-234234x864)
Giúp mình nha
Tính nhanh
2016 x 2018 -1
_____________
2015+2016x2017
2016 × 2018 - 1/2015 + 2016 × 2017
= 2016 × (2017 + 1) - 1/2015 + 2016 × 2017
= 2016 × 2017 + (2016 - 1)/2015 + 2016 × 2017
= 2016 × 2017 + 2015/2015 + 2016 × 2017
= 1
Tính :A= [(2018/1)+(2017/2)+(2016/3)+(2015/4)+...+(4/2015)+(3/2016)+(2/2017)+(1/2018)]/[(2019/2)+(2019/3)+(2019/4)+(2019/5)+...+(2019/2015)+(2019/2016)+(2019/2017)+(2019/2018)+(2019/2019)]
Tính :A= [(2018/1)+(2017/2)+(2016/3)+(2015/4)+...+(4/2015)+(3/2016)+(2/2017)+(1/2018)]/[(2019/1)+(2019/2)+(2019/3)+(2019/4)+...+(2019/2015)+(2019/2016)+(2019/2017)+(2019/2018)+(2019/2019)]
chứng minh 2015/2016 + 2016/2017 + 2017/2018 + 2018/2019 + 2019/2020 + 2020/2015 > 6
Vì:
khi tính bài toán 2015/2016 + 2016/2017 + 2017/2018 + 2018/2019 + 2019/2020 + 2020/2015 này ra thì ta được con số là 6,000003688 con số này phải lớn hơn số 6 nên: 6,000003688 > 6
Vì:khi tính bài toán 2015/2016+2016/2017+2017/2018+2018/2019+ 2019/2020+2020/2015 ta ra được là: 6,000003688 nên: 6,000003688 > 6
2015/2016 + 2016/2017 + 2017/2018 + 2018/2019 + 2019/2020 + 2020/2015 = 6,000003688 vậy: 6,000003688 > 6
So sánh phân số
\(\frac{2015x2016-1}{2015x2016}\)và\(\frac{2016x2017-1}{2016x2017}\)