\(F=1\dfrac{1}{5}\times1\dfrac{1}{6}\times1\dfrac{1}{7}\times\cdot\cdot\cdot\times1\dfrac{1}{2019}\times1\dfrac{1}{2020}\)

\(F=\dfrac{6}{5}\times\dfrac{7}{6}\times\dfrac{8}{7}\times\cdot\cdot\cdot\times\dfrac{2020}{2019}\times\dfrac{2021}{2020}\)

\(F=\dfrac{6\times7\times8\times\cdot\cdot\cdot\times2020\times2021}{5\times6\times7\times\cdot\cdot\cdot\times2019\times2020}\)

\(F=\dfrac{2021}{5}\)

\(f=1^1_5\times1^1_6\times1^1_7\times......\times1^1_{2019}\times1^1_{2022}\)

\(f=\dfrac{6}{5}\times\dfrac{7}{6}\times\dfrac{8}{7}\times....\times\dfrac{2020}{2019}\times\dfrac{2021}{2020}\)

\(f=\dfrac{6\times7\times8\times....\times2020\times2021}{5\times6\times7\times.....\times2019\times2020}\)

\(f=\dfrac{2021}{5}\)

\(#Tarus\)

F=20215

cậu giải thích giùm mình đoạn này với P(x)=x^7-(x+1)x^6+(x+1)x^5-(x+1)x^4+(x+1)x^3-(x+1)x^2+(x+1)x+15

P(x)=x^7-x^7-x^6+x^6+x^5-x^5-x^4+x^4+x^3-x^3-x^2+x^2+x+15

P(x)=x+15=79+15=94

hay giai giup mk may phan nay nhe

cmr cac bieu thuc sau ko phu thuoc vao x:

c)C=x(x^3+x^2-3x-2)-(x^2-2)(x^2+x-1)

e)E=(x+1)(x^2-x+1)-(x-1)(x^2+x+1)

tinh gia tri cua da thuc

b)Q(x)=x^14-10x^13=10x^12-10x^11+...+10x^2-10x+10   voi x=9

c)R(x)=x^4-17x^3+17x^2_17x+20   või=16

d)S(x)=x^10-13x^9+13x^8-13X^7+...+13x^2-13x+10     voi 12

bạn biết cách giải chưa bày mk vs

a, 3/4 ÷ x/6 = 0,75

x/6 = 0,75 ÷ 0,75

x/6 = 1

=> x = 6

Vậy x = 6

b, 2,5 . 45/ x = 5/6

45/x = 5/6  ÷ 2,5

45/x = 1/3

=> x = 45 × 3

=> x = 135

Vậy x = 135

c, x/12 + 121,5 = 121,5

x/12 = 121,5 - 121,5

x/12 = 0

=> x = 0

Vậy x = 0

e, 6/8 = 15/x

3/4 = 15/x

=> x = 20

Vậy x = 20

a) Ta có: \(P\left(x\right)=x^7-80x^6+80x^5-80x^4+...+80x+15\)

\(=x^7-x^6\left(x+1\right)+x^5\left(x+1\right)-...+x\left(x+1\right)+15\)

\(=x^7-x^7-x^6+x^6+x^5-...+x^2+x+15\)

\(=x+15\)

Thay x=79 vào biểu thức \(P\left(x\right)=x+15\), ta được:

\(P\left(79\right)=79+15=94\)

1. tìm x, y biết

a. 6/7:(x+3/5)-5/6=1/3

=> 6/7 :( x + 3/5 ) = 1/3 + 5/6 

=> 6/7 : ( x + 3/5 ) = 2/6 + 5/6 

=> 6/7 : ( x +3/5 )  = 7/6 

=>           x + 3/5  = 6/7 : 7/6 

=>            x + 3/5 = 6/7 . 6/7 

=>             x + 3/5 = 36/49 

=>              x         = 36/49 -3/5

=>              x          = 33/245 

b. (x-1/2) :3/5+2/3=7/9

=> ( x -1/2 ) : 3/5  = 7/9 -2/3

=> ( x -1/2 ) : 3/5  = 7/9 - 6/9 

=> ( x -1/2 ) : 3/5  = 1/9 

=> x -1/2              = 1/9 . 3/5 

=> x -1/2              = 1/15
=> x                     = 1/15 + 1/2 

=> x                     = 17/30 

c. 11/10-3/5:x=2/5

=>        3/5 : x = 11/10 -2/5

=>         3/5 : x = 11/10 -4/10

=>          3/5 : x = 7/10
=>                  x = 3/5 : 7/10

=>                   x = 3/5 . 10/7

=>                    x = 6/7 

.... Lười wá bạn làm tiếp đi! 

các bạn ơi giải hộ mình với ai nhanh tất cả các bài mình tích cho

6, \(x=\dfrac{9}{2}+\dfrac{1}{2}=\dfrac{10}{2}=5\)

7, \(x=-\dfrac{3}{4}-\dfrac{5}{4}=-\dfrac{8}{4}=-2\)

8, \(x=\dfrac{5}{7}-\dfrac{2}{7}=\dfrac{3}{7}\)

9, \(x=\dfrac{1}{3}+\dfrac{4}{3}=\dfrac{5}{3}\)

10, \(x=-\dfrac{7}{2}-\dfrac{5}{2}=-\dfrac{12}{2}=-6\)

\(6,x-\dfrac{1}{2}=\dfrac{9}{2}\Leftrightarrow x=5\)

\(7,x+\dfrac{5}{4}=\dfrac{-3}{4}\Leftrightarrow x=-2\)

\(8,x+\dfrac{2}{7}=\dfrac{5}{7}\Leftrightarrow x=\dfrac{3}{7}\)

\(9,x-\dfrac{4}{3}=\dfrac{1}{3}\Leftrightarrow x=\dfrac{5}{3}\)

\(10,x+\dfrac{5}{2}=\dfrac{-7}{2}\Leftrightarrow x=-6\)

\(x-\dfrac{1}{2}=\dfrac{9}{2}\)

\(x\)        \(=\dfrac{9}{2}+\dfrac{1}{2}=\dfrac{10}{2}=5\)

\(x+\dfrac{5}{4}=\dfrac{-3}{4}\)

\(x\)        \(=\dfrac{-3}{4}+\dfrac{-5}{4}=\dfrac{-8}{4}=-2\)

\(x+\dfrac{2}{7}=\dfrac{5}{7}\)

\(x\)        \(=\dfrac{5}{7}+\dfrac{-2}{7}=\dfrac{3}{7}\)

\(x-\dfrac{4}{3}=\dfrac{1}{3}\)

\(x\)         \(=\dfrac{1}{3}+\dfrac{4}{3}=\dfrac{5}{3}\)

\(x+\dfrac{5}{2}=\dfrac{-7}{2}\)

\(x\)        \(=\dfrac{-7}{2}+\dfrac{-5}{2}=\dfrac{-12}{2}=-6\)