a)2/5x3/4+6/15:4/9x5
b)25/12x18/35x63/24
c)4 và 1/2+1/2:5 và 1/2
giúp mik với đag cần gấp mai mik phải nộp rồi
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HT
4
22 tháng 8 2018
Ta có \(\frac{6}{5}-\frac{1}{4}+\frac{4}{5}-\frac{3}{4}+\frac{1}{2}\)
\(=\left(\frac{6}{5}+\frac{4}{5}\right)-\left(\frac{1}{4}+\frac{3}{4}\right)+\frac{1}{2}\)
\(=2-1+\frac{1}{2}\)
\(=1+\frac{1}{2}\)
\(=\frac{3}{2}\)
22 tháng 8 2018
\(\frac{6}{5}-\frac{1}{4}+\frac{4}{5}-\frac{3}{4}+\frac{1}{2}\)
\(=\left(\frac{6}{5}+\frac{4}{5}\right)-\left(\frac{1}{4}+\frac{3}{4}\right)+\frac{1}{2}\)
\(=\frac{10}{5}-\frac{4}{4}+\frac{1}{2}\)
\(=2-1+\frac{1}{2}\)
\(=1+\frac{1}{2}=\frac{3}{2}\)
NH
1
NT
2
26 tháng 7 2023
\(\dfrac{x}{15}\)+\(\dfrac{x}{12}\)=4/1+1/2=9/2
=>x(\(\dfrac{1}{15}\)+\(\dfrac{1}{12}\))=9/2
=>x\(\cdot\)\(\dfrac{3}{20}\)=9/2
=>x=9/2:3/20=30
Vậy x=30
26 tháng 7 2023
\(\dfrac{x}{15}+\dfrac{x}{12}=\dfrac{9}{2}\Rightarrow\left(\dfrac{1}{15}+\dfrac{1}{12}\right)x=\dfrac{9}{2}\)
\(\Rightarrow\left(\dfrac{12+18}{180}\right)x=\dfrac{9}{2}\Rightarrow\dfrac{30}{180}x=\dfrac{9}{2}\Rightarrow\dfrac{1}{6}x=\dfrac{9}{2}\Rightarrow x=\dfrac{9}{2}.6=27\)
21 tháng 4 2019
Bài 1 :
a, \(\frac{3}{4}:x=\frac{5}{12}\)
\(x=\frac{3}{4}:\frac{5}{12}\)
\(x=\frac{9}{5}\)
b, \(x-\frac{1}{2}=\frac{3}{4}:\frac{3}{2}\)
\(x-\frac{1}{2}=\frac{1}{2}\)
\(x=\frac{1}{2}+\frac{1}{2}\)
\(x=1\)
c, \(1\frac{1}{2}x-\frac{1}{2}=\frac{3}{4}\)
\(\frac{3}{2}x-\frac{1}{2}=\frac{3}{4}\)
\(\frac{3}{2}x=\frac{3}{4}+\frac{1}{2}\)
\(\frac{3}{2}x=\frac{5}{4}\)
\(x=\frac{5}{4}:\frac{3}{2}\)
\(x=\frac{5}{6}\)
21 tháng 4 2019
Bài 2 :
\(A=\frac{-3}{5}+\left(\frac{-2}{5}-99\right)\)
\(A=\frac{-3}{5}+\frac{-2}{5}-99\)
\(A=\left(-1\right)-99\)
\(A=-100\)
\(B=\left(7\frac{2}{3}+2\frac{3}{5}\right)-6\frac{2}{3}\)
\(B=\left(\frac{23}{3}+\frac{13}{5}\right)-\frac{20}{3}\)
\(B=\frac{23}{3}+\frac{13}{5}-\frac{20}{3}\)
\(B=\left(\frac{23}{3}-\frac{20}{3}\right)+\frac{13}{5}\)
\(B=1+\frac{13}{5}\)
\(B=\frac{18}{5}\)
6 tháng 4 2020
bạn đã kiểm tra kĩ chưa vậy?mình đọc đề câu B mà loạn não luôn á;-;
VQ
1
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
2 tháng 8 2023
(3\(x\) - 2)(\(x+4\)) - (1- \(x\))(2-\(x\)) =(\(x+1\))(\(x-2\))
3\(x^2\) + 12\(x\) - 2\(x\) - 8 - (\(x+1\))(\(x-2\)) - [-(\(x-2\))](1- \(x\)) = 0
3\(x^2\) + 10\(x\) - 8 - (\(x-2\))( \(x\) + 1 - 1 + \(x\)) = 0
3\(x^2\) + 10\(x\) - 8 - (\(x-2\)). 2\(x\) = 0
3\(x^2\) + 10\(x\) - 8 - 2\(x^2\) + 4\(x\) = 0
\(x^2\) + 14\(x\) - 8 = 0
\(x^2\) + 7\(x\) + 7\(x\) + 49 - 57 = 0
\(x\)( \(x\) + 7) + 7(\(x\) + 7) = 57
(\(x+7\))(\(x\) + 7) =57
(\(x+7\))2 = 57
\(\left[{}\begin{matrix}x+7=\sqrt{57}\\x+7=-\sqrt{57}\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=-7+\sqrt{57}\\x=-7-\sqrt{57}\end{matrix}\right.\)
Vậy \(x\) \(\in\) { -7 - \(\sqrt{57}\); - 7 + \(\sqrt{57}\)}
25 tháng 5 2021
- \(\frac{2}{3}\)
- \(\frac{7}{4}\)
- \(\frac{6}{2}=3\)
- \(\frac{4}{10}=\frac{2}{5}\)
- \(\frac{5}{7}\)
7 tháng 10 2021
\(a,=a^8-16\\ b,\left(a+c\right)^2-b^2=a^2+2ac+c^2-b^2\\ c,=\left(a^2-b^2\right)\left(a^2+b^2\right)\left(a^4+b^4\right)\\ =\left(a^4-b^4\right)\left(a^4+b^4\right)=a^8-b^8\\ d,=\left[\left(3x+y\right)-2\right]^2=\left(3x+y\right)^2-4\left(3x+y\right)+4\\ =9x^2+6xy+y^2-12x-4y+4\\ h,=x^3+64\\ e,=\left(2^4-1\right)\left(2^4+1\right)\left(2^8+1\right)\\ =\left(2^8-1\right)\left(2^8+1\right)=2^{16}-1=...\\ f,=\left(x+y-x+y\right)\left[\left(x+y\right)^2+\left(x+y\right)\left(x-y\right)+\left(x-y\right)^2\right]\\ =2y\left(x^2+2xy+y^2+x^2-y^2+x^2-2xy+y^2\right)\\ =2y\left(3x^2+y^2\right)\)
a; \(\dfrac{2}{5}\) x \(\dfrac{3}{4}\) + \(\dfrac{6}{15}\) : \(\dfrac{4}{9}\) x 5
= \(\dfrac{3}{10}\) + \(\dfrac{2}{5}\) x \(\dfrac{9}{4}\) x 5
= \(\dfrac{3}{10}\) + \(\dfrac{9}{10}\) x 5
= \(\dfrac{3}{10}\) + \(\dfrac{45}{10}\)
= \(\dfrac{48}{10}\)
= \(\dfrac{24}{5}\)
b; \(\dfrac{25}{12}\) x \(\dfrac{18}{35}\) x \(\dfrac{63}{24}\)
= \(\dfrac{15}{14}\) x \(\dfrac{63}{24}\)
= \(\dfrac{45}{16}\)
c; 4\(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) : 5\(\dfrac{1}{2}\)
= \(\dfrac{9}{2}\) + \(\dfrac{1}{2}\) : \(\dfrac{11}{2}\)
= \(\dfrac{9}{2}\) + \(\dfrac{1}{11}\)
= \(\dfrac{99}{22}\) + \(\dfrac{2}{22}\)
= \(\dfrac{101}{22}\)