$\frac{x-11}{89}+\frac{x-13}{87}+\frac{x-15}{85}+\frac{x-17}{83}=4$$=>\left(\frac{x-11}{89}-1\right)+\left(\frac{x-13}{87}-1\right)+\left(\frac{x-15}{85}-1\right)+\left(\frac{x-17}{83}-1\right)=0$$=>\frac{x-100}{89}+\frac{x-100}{87}+\frac{x-100}{85}+\frac{x-100}{83}=0$$=>\left(x-100\right)\left(\frac{1}{89}+\frac{1}{87}+\frac{1}{85}+\frac{1}{83}\right)=0$=> x-100 =0 => x=100Vậy nghiệm là 100 

ta có 0=\(\frac{x-11}{89}-1+\frac{x-13}{87}-1+\frac{x-15}{85}-1+\frac{x-17}{83}-1=0\)

0=\(\frac{x-11-89}{89}+\frac{x-13-87}{87}+\frac{x-15-85}{85}+\frac{x-17-83}{83}\)

0=\(\frac{x-100}{89}+\frac{x-100}{87}+\frac{x-100}{85}+\frac{x-100}{83}\)

0=(x-100)(\(\frac{1}{89}+\frac{1}{87}+\frac{1}{85}+\frac{1}{83}\))

vì \(\frac{1}{89}+\frac{1}{87}+\frac{1}{85}+\frac{1}{83}\)khác 0      suy ra x-100=0 

                                                                                    x=100

x−11/89+x−13/87+x−15/85+x−17/83=4

=>(x−11/89−1)+(x−13/87−1)+(x−15/85−1)+(x−17/83−1)=0

=>x−100/89+x−100/87+x−100/85+x−100/83=0

=>(x−100)(1/89+1/87+1/85+1/83)=0

=> x-100 =0 

Vậy nghiệm là 100

\(17\cdot85+15\cdot17-120\)

\(=17\cdot\left(85+15\right)-120\)

\(=17\cdot100-120\)

\(=1700-120\)

\(=1580\)

mình cảm ơn

:)))

1580

SSH cua S la : (85 - 15) : 2 + 1 = 36 (so)

Tong S la : (85 + 15) x 36 : 2 = 1800

Khoảng cách là 2.

Số số hạng:

(85 - 15) : 2 + 1 = 36 số hạng

Tổng là:

(85 + 15) x 36 : 2 = 1800

Đáp số: 1800

c.ơn mn nhìu nhoa ..... mik lm đúng oy hjhj

(85+106+17)-(85+17) = 208-102 = 106

(85+106+17)-(85+17)

=(191+17) - 102

=208 - 102

=106

(85+106+17)-(85+17)=106

\(\frac{x+14}{86}+\frac{x+15}{85}+\frac{x+16}{84}+\frac{x+17}{83}+\frac{x+116}{4}=0\)

\(\Leftrightarrow\frac{x+14}{86}+\frac{x+15}{85}+\frac{x+16}{84}+\frac{x+17}{83}+\frac{x+100}{4}+4=0\)

\(\Leftrightarrow\left(\frac{x+14}{86}+1\right)+\left(\frac{x+15}{85}+1\right)+\left(\frac{x+14}{86}+1\right)+\left(\frac{x+13}{87}+1\right)+\frac{x+100}{4}=0\)

\(\Leftrightarrow\frac{x+100}{86}+\frac{x+100}{85}+\frac{x+100}{84}+\frac{x+100}{83}+\frac{x+100}{4}=0\)

\(\Leftrightarrow\left(x+100\right)\left(\frac{1}{86}+\frac{1}{85}+\frac{1}{84}+\frac{1}{83}+\frac{1}{4}\right)=0\)

\(\Leftrightarrow x+100=0\left(vì\frac{1}{86}+\frac{1}{85}+\frac{1}{84}+\frac{1}{83}+\frac{1}{4}\ne0\right)\)

\(\Leftrightarrow x=-100\)

vậy.............................

Kham khảo 

\(\left[\frac{\left(x+14\right)}{86}+1\right]+\left[\frac{\left(x+15\right)}{85}+1\right]+\left[\frac{\left(x+16\right)}{84}+1\right]+\left[\frac{\left(x+17\right)}{83}+1\right]\)\(+\left[\frac{\left(x+116\right)}{4}-4\right]=0\)

\(\frac{\Rightarrow\left(x+100\right)}{86}+\frac{\left(x+100\right)}{85}+\frac{\left(x+100\right)}{84}+\frac{\left(x+100\right)}{83}+\frac{\left(x+100\right)}{16}=0\)

\(\Rightarrow\left(x+100\right)\left(\frac{1}{86}+\frac{1}{85}+\frac{1}{84}+\frac{1}{83}+\frac{1}{16}\right)=0\)

\(\Leftrightarrow x+100=0\Rightarrow x=-100\)

Mặt khác :\(\frac{1}{86}+\frac{1}{85}+\frac{1}{84}+\frac{1}{83}+\frac{1}{16}\ne0\)

Vậy x=-100

_Chúc bn hc tốt

giúp mik với huhu

=-65*85+65*17-85*17+85*65

=17*(-20)

=-340

( 85- 106- 17 ) - ( 85 + 17)

= ( -21- 17 )- 102

= -38 - 102

= - 140

(85-106-17)-(85+17)

=(-21 - 17) - 102

= (-38) -102

= - 140

(85-106-17)-(85+17)

=(-21-17)-102

=-38-102

=-140

P = { 13 ; 15 ; 17 ; ... ; 85 ; 87 } có ( 87 - 13 ) : 2 + 1 = 38 ( phần tử)
 

38 phan tu

38 đó bạn

mk thi đúng ak!!!1