rút gọn:
$\frac{2.(-13).9.10}{(-3).4.(-5).26}$ =
tìm x
x-$\frac{1}{13}$ =$\frac{-5}{9}$
$\frac{-5}{6}$ – x =$\frac{7}{12}$ +$\frac{-1}{3}$
|2x+3|-5=0
tìm n thuộc Z sao cho:
(3n+1) chia hết cho (n+2) ∈ ∈ ⇒ ∈
rút gọn: $\frac{2.(-13).9.10}{(-3).4.(-5).26}$ = tìm x x-$\frac{1}{13}$ =$\frac{-5}{9}$ $\frac{-5}{6}$ – x =$\frac{7}{12}$ +$\frac{-1}{3}$ |2x+3|-5
By Remi
Đáp án:
↓↓↓
Giải thích các bước giải:
`a,(2.(-13).9.10)/((-3).4.(-5).26`
`=(2.(-13).3.3.5.2)/((-3).2.2.(-5).13.2)`
`=-3/2`
`b,x-1/13=-5/9`
`⇒x=-5/9+1/13`
`⇒x=-56/117`
`c,-5/6-x=7/12+(-1)/3`
`⇒-5/6-x=1/4`
`⇒-x=13/12`
`⇒x=-13/12`
`d,|2x+3|-5=0`
`⇒|2x+3|=5`
`⇒`\(\left[ \begin{array}{l}2x+3=5\\2x+3=-5\end{array} \right.\)
`⇒`\(\left[ \begin{array}{l}x=1\\x=-4\end{array} \right.\)
`e,(3n+1)` chia hết cho `(n+2)`
`⇒(3n+6-5)` chia hết cho `(n+2)`
`⇒5` chia hết cho `(n+2)`
`⇒(n+2)∈ Ư(5)`
`⇒`\(\left[ \begin{array}{l}n+2=5\\n+2=-5\\n+2=1\\n+2=-1\end{array} \right.\)
`⇒`\(\left[ \begin{array}{l}n=3\\n+=-7\\n=-1\\n=-3\end{array} \right.\)
Đáp án + Giải thích các bước giải:
Bài `1:`
`( 2 . (-13) . 9 . 10 )/((-3) . 4 . (-5) . 26 ) = (2.(-13) . 3 . 3 . 2 . 5)/((-3) . 2 . 2 .(-5) . 2 . 13)=-3/2`
Bài `2:`
`a) x-1/13=(-5)/9`
`=> x=(-5)/9+1/13`
`=> x=-56/117`
Vậy `x=-56/117`
`b) (-5)/6-x=7/12+(-1/3)`
`=> (-5)/6-x=1/4`
`=> x=(-5)/6-1/4`
`=> x=-13/12`
Vậy `x=-13/12`
`c) |2x+3|-5=0`
`=> |2x+3|=5`
`=>` \(\left[ \begin{array}{l}2x+3=5\\2x+3=-5\end{array} \right.\) `=>`\(\left[ \begin{array}{l}2x=2\\2x=-8\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=1\\x=-4\end{array} \right.\) `
Vậy `x=1` hoặc `x=-4`
Bài `3:`
`3n+1 vdots n+2`
`=> 3n+6-5 vdots n+2`
`=> 3(n+2)-5 vdots n+2`
`=> 5 vdots n+2`
`=> n+2 in Ư(5)={-5;-1;1;5}`
`=> n in {-7;-3;-1;3}`
Vậy `n in {-7;-3;-1;3}`