Question

B2: tìmX

A.13 x X+ 14 x X=50

B. ( X+2) +( X+4) +…+  (X+ 100)=3550

C.(1- X)+(2- X)+ (3- X)+…+ (100- X)=50

D. ( X+1)+(2x X+3)+(3 x X+5)+…+(50 x X +99)= 3775

K. 5 x X-(1+2+3+…+30)=135

M. X- 165

                  + 546= 562

        X

 

Answer 1

A. \(13x+14x=50\)

\(\Leftrightarrow17x=50\)

\(\Leftrightarrow x=\frac{50}{17}\)

Answer 2

a) 13x+14x = 50

=> x.(13+14)=50

x+27=50

x = 50-27

x=23 ( bài này ko chắc lắm )

b) (x+2)+(x+4)+...+(x+100)=3550

=> có 50 cặp như vậy 

(x+x+x+...+x)+(2+4+...+100)=3550

<=>50x+2550=3550

50x=3550-2550

50x=1000

x=1000:50

x=20

c) (1-x)+(2-x)+...+(100-x)=50

=> có 100 như vậy

(1+2+3+...+100)-(x+x+x+...+x)=50

<=>5050-100x=50

100x=5050-50

100x=5000

x=5000:100

x=50

d) để mình nghĩ cách làm lại đã rồi mình sẽ trả lời lại sau

k) 5x-(1+2+3+...+30)=135

5x-465=135

5x=135+465

5x=600

x=600:5

x=120

m) \(\frac{x-165}{x}\)+546=562

\(\frac{x-165}{x}\)=562-546

\(\frac{x-165}{x}\)=16

\(\Rightarrow\frac{x-165}{x}=\frac{16}{1}\)

<=> x-165=16

x=16+165

x=181 ( ko chắc )

Answer 3

d) (1x+1)+(2x+3)+(3x+5)+...+(50x+99)=3775

<=> (1x+2x+3x+...+50x)+(1+3+5+...+99)=3775

=> (1x+2x+3x+...+50x)+2500=3775

=> (1x+2x+3x+...+50x)=3775-2500

=> (1x+2x+3x+...+50x)=1275

<=> [x(1+2+3+...+50)]=1275

=> x.1275=1275

x=1275:1275

x=1