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Câu a:
\(\frac{x+5}{x+9}\) = \(\frac{x+4}{x+3}\)
(\(x\) + 5)(\(x+3\)) = (\(x+4\))(\(x+9\))
\(x^2\) + 3\(x\) + 5\(x\) + 15 = \(x^2\) + 9\(x\) + 4\(x\) + 36
\(x^2+3x+5x\) - \(x^2-9x\) - 4\(x\) = 36 - 15
(\(x^2-x^2\)) + (\(3x+5x\) - 9\(x-4x\)) = 21
0 + (8\(x\) - 9\(x\) - 4\(x\)) = 21
-\(x-4x\) = 21
-5\(x\) = 21
\(x\) = 21 : (-5)
\(x\) = - \(\frac{21}{5}\)
Vậy \(x=-\frac{21}{5}\)
â, -4/9(7/15+8/15)=-4/9
b,-5/4(16/25+9/25)=-5/4
,.....
dài quá mik làm ko hết
hok tốt
a)\(\frac{-4}{9}\times\frac{7}{15}+\frac{-4}{9}\times\frac{8}{15}\)
= \(\frac{-4}{9}\times\left(\frac{7}{15}+\frac{8}{15}\right)\)
=\(-\frac49\times1\)
=\(-\frac49\)
\(\frac{2x}{3}=\frac{7x-3}{15}\)
\(\Rightarrow30x=3\left(7x-3\right)\)
\(30x=21x-9\)
\(9x=-9\)
\(x=-1\)
\(\frac{11x-2}{7x+5}=\frac{11}{8}\)
\(\Rightarrow8\left(11x-2\right)=11\left(7x+5\right)\)
\(88x-16=77x+55\)
\(11x=71\)
\(x=\frac{71}{11}\)
\(\frac{2x+3}{3x+1}=\frac{3}{4}\)
\(\Rightarrow4\left(2x+3\right)=3\left(3x+1\right)\)
\(8x+12=9x+3\)
\(-x=-9\)
\(x=9\)
mk lộn đề câu a
bn giải lại giùm mk nha
\(\frac{2x+3}{6}=\frac{7x-3}{15}\)
\(\frac37+\frac{5}{13}+\frac{4}{13}\)
=\(\frac37+\left(\frac{5}{13}+\frac{4}{13}\right)\)
=\(\frac37+\frac{9}{13}\)
=\(\frac{39}{91}+\frac{63}{91}\)
=\(\frac{102}{91}\)
\(\left(\frac38+\frac{-3}{4}+\frac{7}{12}\right):\frac56+\frac12\)
=\(\left(\frac{9}{24}+\frac{-18}{24}+\frac{7}{24}\right)\times\frac65+\frac12\)
=\(\frac{5}{24}\times\frac65+\frac12\)
=\(\frac14+\frac12\)
=\(\frac14+\frac24\)
=\(\frac34\)
a) 3. ( x - 2/5 ) = 0
<=> x = 0 : 3 + 2/5
<=> x = 2/5
( Theo cách lớp 6)
Hoặc cách thông thường nek:
3. ( x - 2/5 ) = 0
x - 2/5 = 0 : 3
x - 2/5 = 0
x = 0 + 2/5
x = 2/5
Mấy câu sau làm như vậy nha!
^^ Chúc học tốt!!!!
a) \(3x+7x-13=27\)
\(10x=40\)
\(\Rightarrow x=4\)
vay \(x=4\)
b) \(\frac{6x-11}{3}+\frac{4}{5}=\frac{14}{15}\)
\(\frac{6x-11}{3}=\frac{14}{15}-\frac{4}{5}\)
\(\frac{6x-11}{3}=\frac{14}{15}-\frac{12}{15}\)
\(\frac{6x-11}{3}=\frac{2}{15}\)
\(\Rightarrow\left(6x-11\right).15=3.2\)
\(\Rightarrow90x-165=6\)
\(\Rightarrow90x=171\)
\(\Rightarrow x=\frac{19}{10}\)
vay \(x=\frac{19}{10}\)
a)\(3x+7x-13=27\)
\(\Leftrightarrow\left(3x+7x\right)=27+13\)
\(\Leftrightarrow10x=40\)
\(\Rightarrow x=40\div10\)
\(\Rightarrow x=4\)
a)X = 4
B) x = 1,9
b) \(\frac{6x-11}{3}=\frac{14}{15}-\frac{4}{5}\)
\(\frac{6x-11}{3}=\frac{2}{15}\)
6x-11=\(\frac{3\cdot2}{15}=\frac{2}{5}\)
6x=57/5
x=19/10
câu a mk ko thấy x đâu nha bn chuc bn hoc tot
a) 3x + 7x - 13 = 27
10x = 27 + 13
10x = 40
=> x = 4
\(b,\frac{6x-11}{3}+\frac{4}{5}=\frac{14}{15}\)
\(\frac{6x-11}{3}=\frac{14}{15}+\frac{4}{5}\)
\(\frac{6x-11}{3}=\frac{26}{15}\)
\(\frac{\left(6x-11\right)\cdot5}{15}=\frac{26}{15}\)
\(\Rightarrow\left(6x-11\right)\cdot5=26\)
\(\Rightarrow6x-11=26:5\)
\(\Rightarrow6x-11=5,2\)
\(\Rightarrow6x=5,2+11\)
\(\Rightarrow6x=16,2\)
\(\Rightarrow x=2,7\)
a) 4
b) 1,9