tinh nhanh tong sau 1 phan 2 cong 1 phan 4 cong 1 phan 8 cong 1 phan 10 cong 1 phan 16 cong 1 phan 32 cong 1 phan 64 cong 1 phan 128
tinh nhanh 4 phan 5 cong 2 phan 7 cong 11 phan 5 cong 12 phan 7 cong 1 phan 5
\(\frac{4}{5}+\frac{2}{7}+\frac{11}{5}+\frac{12}{7}+\frac{1}{5}\)
\(=\frac{4}{5}+\frac{11}{5}+\frac{1}{5}+\frac{2}{7}+\frac{12}{7}\)
\(=\frac{4+11+1}{5}+\frac{2+12}{7}\)
\(=\frac{16}{5}+\frac{14}{7}\)
\(=\frac{16}{5}+2=\frac{26}{5}\)
\(\frac{4}{5}+\frac{2}{7}+\frac{11}{5}+\frac{12}{7}+\frac{1}{5}\)
\(=\left(\frac{4}{5}+\frac{11}{5}+\frac{1}{5}\right)+\left(\frac{2}{7}+\frac{12}{7}\right)\)
\(=\frac{16}{5}+\frac{14}{7}\)
\(=\frac{16}{5}+2=\frac{16}{5}+\frac{10}{5}=\frac{26}{5}\)
\(\frac{4}{5}+\frac{2}{7}+\frac{11}{5}+\frac{12}{7}+\frac{1}{5}\)
\(=\left(\frac{4}{5}+\frac{11}{5}+\frac{1}{5}\right)+\left(\frac{2}{7}+\frac{12}{7}\right)\)
\(=\frac{16}{5}+2\)
\(=\frac{26}{5}\)
tim z,y,z thoa
can x cong can tat ca y tru 1 cong can tat ca z tru 2 bang 1 phan 2 ( x cong y cong z)
tim GTN cua B bang 1 phan x tru can x cong 1
tim x thuoc z de can x cong 1 phan can 3 tru 3 la so nguyen
tinh tong T bang 1 phan can 1 cong can 2 cong 1 phan can 2 cong can 3 cong ... cong den 1 phan can 99 cong can 100
mot nha may co 3 phan xuong . so cong nhan cua phan xuong 1 bang 36% tong so cong nhan nha may so cong nhan cua phan xuong 2 bang 3/5 so cong nhan cua phan xuong 3 . biet so cong nhan cua phan xuong 3 hon so cong nhan cua phan xuong 1 la 18 nguoi . tinh so nguoi moi phan xuong
Cho A bang 1 phan 11 cong 1 phan 12 cong 1 phan 13 cong......cong 1 phan 39 cong 1 phan 40
Chung minh A lon hon 3 phan 4
Ta có 1/11; 1/12; 1/13;...; 1/39 > 1/40
\(\Rightarrow\) A = 1/11 + 1/12 + 1/13 +...+ 1/39 +1/40 > 1/40 + 1/40 + 1/40 +...+ 1/40 + 1/40(có 30 số hạng)
A > 30/40
Mà 30/40 =3/4 nên A >3/4
Vậy A > 3/4
tinh tong sau 1 cong 1tren 2 cong 1 tren 3 cong 1 phan 4
1 + 1/2 + 1/3 + 1/4
= 12/12 + 6/12 + 4/12 + 3/12
= 25/12
#Tề _ Thiên
1 + \(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}\)
= \(\frac{12}{12}+\frac{6}{12}+\frac{4}{12}+\frac{3}{12}\)
= \(\frac{25}{12}\)
Trả lời : \(1+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}\)
\(=\frac{12}{12}+\frac{6}{12}+\frac{4}{12}+\frac{3}{12}\)
\(=\frac{25}{12}\)
\(\downarrow\)
1 phan 6 cong 3 phan 4 cong 1 phan 8
\(\dfrac{1}{6}+\dfrac{3}{4}+\dfrac{1}{8}=\dfrac{4}{24}+\dfrac{18}{24}+\dfrac{3}{24}=\dfrac{25}{24}\)
3 phan 1 nhan 4 cong 3 phan 4 nhan 7 cong 3 phan 7 nhan 10 cong ... cong 3 phan 40 nhan 43
#)Giải :
Gọi tổng trên là A
\(A=\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+...+\frac{3}{40.43}\)
\(A=3-\frac{3}{4}+\frac{3}{4}-\frac{3}{7}+\frac{3}{7}-\frac{3}{10}+...+\frac{3}{40}-\frac{3}{43}\)
\(A=3-\frac{3}{43}\)
\(A=3\frac{3}{43}=\frac{132}{43}\)
#~Will~be~Pens~#
Mot xi nghiep co 2 phan xuong. So cong nhan o phan xuong thu nhat bang 2/5 so cong nhan phan xuong thu hai . Cuoi nam co 22 cong nhan chuyen tu phan xuong 2 sang phan xuong 1 nen so cong nhan phan xuong 1 bang 5/7 so cong nhan phan xuong 2 tinh so cong nhan moi phan xuong ?
1phan 2 cong 1phan 6 cong 1 phan 12 cong 1phan 20 cong 1phan 30 cong mot phan 42 cong mot phan 56 cong mot phan 72 =????