fan vu liz 

= 3.75 * (6.8 - 6.8)

= 3.75 * 0

= 0

3.75*6.8-6.8*3.75

= 6,8 x ( 3,75 - 3,75 )

= 6,8 x 0

= 6,8

\(\frac{2^{15}.9^4}{6^6.8^3}=\frac{2^{15}.\left(3^2\right)^4}{\left(2.3\right)^6.\left(2^3\right)^3}=\frac{2^{15}.3^8}{2^6.3^6.2^9}=\frac{2^{15}.3^8}{2^{15}.3^6}=3^2=9\)

\(\left(y-6.8\right):8.7=6.8\)

\(\Leftrightarrow\left(y-48\right):56=48\)

\(\Leftrightarrow y-48=48.56\)

\(\Leftrightarrow y-48=2688\)

\(\Leftrightarrow y=2688+48\)

\(\Leftrightarrow y=2736\)

bằng 65,96 nhé

y - 6,8 = 6,8 x 8,7

y - 6,8 = 59,16

y         = 59,16 + 6,8

y         = 65,96

 Ủng hộ mik nha

đề lk gì man

nhớ đặt tính nha

thank your

lần lượt là:

2;4;4;0,4;67,5

-Đề bài là gì ạ?

Trường hợp 1: 6.8^x-1=6.8^21

x-1=19

x=19+1

x=20

vậy x=20

Trương hợp 2: 8^x+1=8^21

x+1=21

x=21-1

x=20

vậy x=20

6.8^x-1+8^x+1=6.8^19+8^21

<>6.8^x-1+8^x-1.8^2=6.8^19+8^19.8^2

 <>8^x-1(6+8^2)=8^19(6+8^2)

<>8^x-1=8^19

<>x-1=19

<>x=19+1=20

\(N=\dfrac{4}{2.4}+\dfrac{4}{4.6}+\dfrac{4}{6.8}+...+\dfrac{4}{2014.2016}\)

\(=2\left(\dfrac{2}{2.4}+\dfrac{2}{4.6}+\dfrac{2}{6.8}+...+\dfrac{2}{2014.2016}\right)\)

\(=2\left(\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{8}+...+\dfrac{1}{2014}-\dfrac{1}{2016}\right)\)

\(=2\left(\dfrac{1}{2}-\dfrac{1}{2016}\right)\)

\(=2\left(\dfrac{1008}{2016}-\dfrac{1}{2016}\right)\)

\(=2.\dfrac{1007}{2016}=\dfrac{1007}{1008}\)

Công thức đây bạn:

\(\dfrac{a}{n\left(n+a\right)}=\dfrac{1}{n}-\dfrac{1}{n+a}\)

Giải:

\(N=\dfrac{4}{2.4}+\dfrac{4}{4.6}+\dfrac{4}{6.8}+...+\dfrac{4}{2014.2016}\) 

\(N=2.\left(\dfrac{2}{2.4}+\dfrac{2}{4.6}+\dfrac{2}{6.8}+...+\dfrac{2}{2014.2016}\right)\) 

\(N=2.\left(\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{8}+...+\dfrac{1}{2014}-\dfrac{1}{2016}\right)\) 

\(N=2.\left(\dfrac{1}{2}-\dfrac{1}{2016}\right)\) 

\(N=2.\dfrac{1007}{2016}\) 

\(N=\dfrac{1007}{1008}\) 

Công thức tính: \(\dfrac{1}{n.\left(n+1\right)}=\dfrac{1}{n}-\dfrac{1}{n+1}\) 

Chúc bạn học tốt!

\(\frac{1}{2.4}+\frac{1}{4.6}+....+\frac{1}{2016.2018}\)

\(=\frac{1}{2}.\left(\frac{2}{2.4}+\frac{2}{4.6}+...+\frac{2}{2016.2018}\right)\)

\(=\frac{1}{2}.\left(\frac{1}{2}-\frac{1}{2018}\right)=\frac{1}{2}.\frac{504}{1009}=\frac{252}{1009}\)

mơn bn nha

\(\frac{1}{2.4}+\frac{1}{4.6}+\frac{1}{6.8}+...+\frac{1}{2016.2018}\)

\(=\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{6}+...+\frac{1}{2016}-\frac{1}{2018}\)

\(=\frac{1}{2}+\left(-\frac{1}{4}+\frac{1}{4}\right)+\left(-\frac{1}{6}+\frac{1}{6}\right)+...+\left(-\frac{1}{2016}+\frac{1}{2016}\right)-\frac{1}{2018}\)

\(=\frac{1}{2}+0+0+0+...+0-\frac{1}{2018}\)

\(=\frac{1}{2}-\frac{1}{2018}\)

\(=\frac{1009}{2018}-\frac{1}{2018}\)

\(=\frac{1008}{2018}=\frac{504}{1009}\)

Ai thấy tớ đúng k nha