$\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

`@` `\text {Ans}`

`\downarrow`

`a)`

`-9/34*17/4`

`=`\(\dfrac{-9}{17\cdot2}\cdot\dfrac{17}{4}\)

`=`\(-\dfrac{9}{2}\cdot\dfrac{1}{4}\)

`=`\(-\dfrac{9}{8}\)

`b)`

\(\dfrac{17}{15}\div\dfrac{4}{3}\)

`=`\(\dfrac{17}{15}\cdot\dfrac{3}{4}\)

`=`\(\dfrac{17}{3\cdot5}\cdot\dfrac{3}{4}\)

`=`\(\dfrac{17}{5}\cdot\dfrac{1}{4}\)

`=`\(\dfrac{17}{20}\)

`c)`

\(4\dfrac{1}{5}\div\left(-2\dfrac{4}{5}\right)\)

`=`\(4\dfrac{1}{5}\cdot\left(-\dfrac{5}{14}\right)\)

`=`\(\dfrac{21}{5}\cdot\left(-\dfrac{5}{14}\right)\)

`=`\(-\dfrac{21}{14}=-\dfrac{3}{2}\)

a) \(\dfrac{-9}{34}\cdot\dfrac{17}{4}\)

\(=\dfrac{-9\cdot17}{34\cdot4}\)

\(=-\dfrac{153}{136}\)

\(=\dfrac{9}{8}\)

b) \(\dfrac{17}{15}:\dfrac{4}{3}\)

\(=\dfrac{17}{15}\cdot\dfrac{3}{4}\)

\(=\dfrac{17\cdot3}{15\cdot4}\)

\(=\dfrac{51}{60}=\dfrac{17}{20}\)

c) \(4\dfrac{1}{5}:\left(-2\dfrac{4}{5}\right)\)

\(=\dfrac{21}{5}:-\dfrac{14}{5}\)

\(=\dfrac{21}{5}\cdot-\dfrac{5}{14}\)

\(=\dfrac{21\cdot-5}{5\cdot14}\)

\(=-\dfrac{105}{70}=\dfrac{3}{2}\)

a) −934⋅17434−9​⋅417​

=−9⋅1734⋅4=34⋅4−9⋅17​

=−153136=−136153​

=98=89​

b) 1715:431517​:34​

=1715⋅34=1517​⋅43​

=17⋅315⋅4=15⋅417⋅3​

=5160=1720=6051​=2017​

c) 415:(−245)451​:(−254​)

=215:−145=521​:−514​

=215⋅−514=521​⋅−145​

=21⋅−55⋅14=5⋅1421⋅−5​

=−10570=32=−70105​=2

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

làm hộ mình bài 4 nhé .

= 85 x (-18) - 18 x (-15)

= -1530 + 270  =  -1260

trả lời

valentine vui vẻ nhé. nếu bn fa thì chúc bn sớm tìm dc nửa iu thưn, cn nếu bn có ny thì mk chúc ny bn và bn sẽ bên nhao mãi mãi

học tốt

=-1260

valentine vui vẻ