Question

[Ngo Hong Phuc]

tinh hoac tinh nhanh neu co the

a 35×17+84×35-35

b5/2×1/3-1/4

c(1-1/2)×(1-1/3)×(1-1/4)×(1-1/4)×....×(1-1/2017)×(1-1/2018)

ban nao lam dung 3 cau minh tich cho moi ngay khong duoc lam tat

Answer 1

[Không Tên]

a)  \(35\times17+84\times35-35\)

\(=35\times\left(17+84-1\right)\)

\(=35\times100=3500\)

b)  \(\frac{5}{2}\times\frac{1}{3}-\frac{1}{4}=\frac{5}{6}-\frac{1}{4}=\frac{7}{12}\)

c)  \(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right)\left(1-\frac{1}{4}\right).....\left(1-\frac{1}{2017}\right)\left(1-\frac{1}{2018}\right)\)

\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.....\frac{2016}{2017}.\frac{2017}{2018}\)

\(=\frac{1}{2018}\)

Answer 2

[nguyen khac hoang phuc]

a)35x17+84x35-35

=35x(17+84-1)

=35x100

=3500

b)5/2x1/3-1/4

=5/6-1/4

=7/12

c)(1-1/2)x(1-1/3)x(1-1/4)x......x(1-1/2018)

=1/2x2/3x3/4x...x2017/2018

=1/2018

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