online math
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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Lời giải:
a. $A(x)=(3x^4+x^4)+\frac{1}{3}x^3+(-x^2+2x^2)+(-x)+(5-2)$
$=4x^4+\frac{1}{3}x^3+x^2-x+3$
b. $B(x)=(5x^5-5x^5)+(-x^4+2x^4)+x^3+(-2x^2-3x^2)+4$
$=x^4+x^3-5x^2+4$
c. $C(x)=(-x^5+3x^5)+(2x^4-x^4)+(2x^3)+(-x^2-2x^2)+1$
$=2x^5+x^4+2x^3-3x^2+1$
![](https://rs.olm.vn/images/avt/0.png?1311)
Đổi: 100kg=1 tạ
20 tạ thóc cho số kg gạo là: 70(20:1)= 1400(kg)
Đổi 20 tạ = 2000 kg
20 tạ thóc cho số ki-lô-gam gạo là:
70 x (2000 : 100) = 1400 (kg)
Kết luận:..
![](https://rs.olm.vn/images/avt/0.png?1311)
a; 5\(x\) - 7 = 3\(x\) + 9
5\(x\) - 3\(x\) = 9 + 7
2\(x\) = 16
\(x\) = 16: 2
\(x\) = 8
Vậy \(x=8\)
b; 1\(\dfrac{3}{4}\)\(x\) + 1\(\dfrac{1}{2}\) = - \(\dfrac{4}{5}\)
\(\dfrac{7}{4}\)\(x\) + \(\dfrac{3}{2}\) = - \(\dfrac{4}{5}\)
\(\dfrac{7}{4}\)\(x\) = - \(\dfrac{4}{5}\) - \(\dfrac{3}{2}\)
\(\dfrac{7}{4}\)\(x\) = - \(\dfrac{23}{10}\)
\(x\) = - \(\dfrac{23}{10}\) : \(\dfrac{7}{4}\)
\(x\) = - \(\dfrac{46}{35}\)
Vậy \(x=-\dfrac{46}{35}\)
c; \(x\) + \(\dfrac{1}{2}\) = 25:23
\(x\) + \(\dfrac{1}{2}\) = 22
\(x\) + \(\dfrac{1}{2}\) = 4
\(x\) = 4 - \(\dfrac{1}{2}\)
\(x\) = \(\dfrac{7}{2}\)
Vậy \(x=\dfrac{7}{2}\)
d; (\(x+\dfrac{1}{2}\))2 = \(\dfrac{4}{25}\)
\(\left[{}\begin{matrix}x+\dfrac{1}{2}=-\dfrac{2}{5}\\x+\dfrac{1}{2}=\dfrac{2}{5}\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=-\dfrac{2}{5}-\dfrac{1}{2}\\x=-\dfrac{2}{5}+\dfrac{1}{2}\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=-\dfrac{9}{10}\\x=-\dfrac{1}{10}\end{matrix}\right.\)
vậy \(x\) \(\in\) {- \(\dfrac{9}{10}\); - \(\dfrac{1}{10}\)}
![](https://rs.olm.vn/images/avt/0.png?1311)
2.(\(\dfrac{1}{4}\) - 3\(x\)) = \(\dfrac{1}{5}\) - 4\(x\)
\(\dfrac{1}{2}\) - 6\(x\) = \(\dfrac{1}{5}\) - 4\(x\)
- 4\(x\) + 6\(x\) =\(\dfrac{1}{2}\) - \(\dfrac{1}{5}\)
2\(x\) = \(\dfrac{3}{10}\)
\(x\) = \(\dfrac{3}{10}\): 2
\(x=\dfrac{3}{20}\)
Vậy \(x=\dfrac{3}{20}\)
Olm chào em, em cần làm gì với dòng chữ này?