15)1,2 x 82 x 2 +0,8 x 18 x 3
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) x x 0,8 = 1,2 x 4,5
x x 0,8 = 5,4
x = 5,4 : 0,8
x = 6,75
Vậy x = 6,75.
b) 45,54 : x = 18 : 5
45,54 : x = 3,6
x = 45,54 : 3,6
x = 12,65
Vậy x = 12,65.
![](https://rs.olm.vn/images/avt/0.png?1311)
0,8 nhân x = 1,2 nhân 10
0,8 nhân x = 12
x = 12 : 0,8
x = 15
210 : x =14,92 -6,52
210 : x = 8,4
x = 210 : 8,4
x = 25
15 : x = 16 : 1,6
15 : x = 10
x = 15 : 10
x = 1,5
0.8 . x = 1,2 x 10
0,8 .x = 12
x =12 : 0,8
x = 15
210 :x = 14,92 - 6,52
210 :x = 8,4
x = 210 : 8,4
x = 25
15 : x = 16 :1,6
15 : x = 10
x = 15 : 10
x = 1,5
Hok tốt ^^
![](https://rs.olm.vn/images/avt/0.png?1311)
a. 1,2−(x−0,8)=−2(0,9+x)1,2−(x−0,8)=−2(0,9+x)
⇔1,2−x+0,8=−1,8−2x⇔1,2−x+0,8=−1,8−2x
⇔−x+2x=−1,8−2⇔x=−3,8⇔−x+2x=−1,8−2⇔x=−3,8
Phương trình có nghiệm x = -3,8
b. 2,3x−2(0,7+2x)=3,6−1,7x2,3x−2(0,7+2x)=3,6−1,7x
⇔2,3x−1,4−4x=3,6−1,7x⇔2,3x−4x+1,7x=3,6+1,4⇔0x=5
a. 1.2-(x-0.8)=-2(0.9+x)1.2-(x-0.8)=-2(0.9+x)
<=>1.2-x+0.8=(-1.8-2x)1.2-x+0.8=-1.8-2x
<=>1.2-x+0.8+1.8+2x=-2.16-2.4x+0.8
<=>-x+2x+2.4x=-1.2-0.8-1.8-2.16+0.8
<=>3.4x=-5.16
<=>x=-5.16/3.4
<=>x=-258/17
![](https://rs.olm.vn/images/avt/0.png?1311)
\(1,2\cdot35+2,56:0,8+58\\ =42+3,2+58\\ =103,2\\ \\ \left(23+15:2,5\right):14,5+17\\ =\left(23+6\right):14,5+17\\ =29:14,5+17=2+17\\ =19\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1: Tìm x
a) Ta có: \(\dfrac{4}{3}:0.8=\dfrac{2}{3}:\left(0.1\cdot x\right)\)
\(\Leftrightarrow\dfrac{2}{3}:\left(\dfrac{1}{10}\cdot x\right)=\dfrac{4}{3}:\dfrac{4}{5}\)
\(\Leftrightarrow\dfrac{2}{3}:\left(\dfrac{1}{10}\cdot x\right)=\dfrac{4}{3}\cdot\dfrac{5}{4}=\dfrac{5}{3}\)
\(\Leftrightarrow x\cdot\dfrac{1}{10}=\dfrac{2}{3}:\dfrac{5}{3}=\dfrac{2}{3}\cdot\dfrac{3}{5}=\dfrac{2}{5}\)
\(\Leftrightarrow x=\dfrac{2}{5}:\dfrac{1}{10}=\dfrac{2}{5}\cdot10=\dfrac{20}{5}=4\)
Vậy: x=4
b) Ta có: \(\left|x\right|=-1.2\)
mà \(\left|x\right|\ge0\forall x\)
nên \(x\in\varnothing\)
Vậy: \(x\in\varnothing\)
Bài 2: Tính
a) Ta có: \(\left(-2.5\right)\cdot\left(-4\right)\cdot\left(-7.9\right)\)
\(=\left(2.5\cdot4\right)\cdot\left(-7.9\right)\)
\(=-7.9\cdot10=-79\)
b) Ta có: \(\left(-0.375\right)\cdot\dfrac{13}{3}\cdot\left(-2\right)^3\)
\(=\dfrac{3}{8}\cdot8\cdot\dfrac{13}{3}\)
\(=3\cdot\dfrac{13}{3}=13\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{x+1}{x+2}=\frac{0,8}{1,2}\)
\(\Rightarrow\frac{x+1}{x+2}=\frac{2}{3}\)
Để \(\frac{x+1}{x+2}=\frac{2}{3}\)
<=> (x+1).3=(x+2).2
=> 3x+3.1=2x+2.2
=> 3x+3 =2x+4
=> 3x-2x =4-3
=> (3-2).x =1
=> x =1
Vậy x=1
Chúc các bạn học tốt
x+1x+2 =0,81,2
⇒x+1x+2 =23
Để x+1x+2 =23
<=> (x+1).3=(x+2).2
=> 3x+3.1=2x+2.2
=> 3x+3 =2x+4
=> 3x-2x =4-3
=> (3-2).x =1
=> x =1
Vậy x=1
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\text{Áp dụng t/c tỉ lệ thức ta có thể b/đ như sau:}\)
\(\frac{x+1}{x+2}=\frac{2}{3}\Rightarrow\left(x+1\right)3=\left(x+2\right)2\)
\(\Rightarrow3x+3=2x+4\)
\(\Rightarrow2x-3x=3-4\)
\(\Rightarrow-x=-1\)
\(\Rightarrow x=1\)