(\(\frac{3}{5}\)-\(\frac{6}{7}\)) : \(\frac{2x}{3}\)=\(\frac{-11}{18}\)
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a, 2(4x - 7 ) = 3(x + 1) + 18
⇌ 8x -14 = 3x + 3 + 18
⇌ 5x = 35 ⇌ x = 7
→ S = \(\left\{7\right\}\)
b, ( 2x - 1 )2 - 4x ( x - 3 ) = -11
⇌ 4x2 - 2x + 1 - 4x2 + 12 = -11
⇌ 10x = -12
⇌ x = \(-\frac{12}{10}\)
→ S = \(\left\{-\frac{12}{10}\right\}\)
c, ( 2x - 5 )2 - ( x + 2 )2 = 0
⇌ ( 2x - 5 -x + 2 )2 = 0
⇌ ( x - 3 )2 = 0
⇌ x - 3 = 0 ⇌ x = 3
→ S = \(\left\{3\right\}\)
d, ( x - 6 ) ( x + 1 ) = 2(x + 1)
⇌ ( x - 6 - 2 ) ( x+ 1) = 0
⇌ x2 - 7x - 8 =0
⇌ ( x - 8 ) ( x + 1 ) = 0
⇒\(\left\{{}\begin{matrix}x-8=0\\x+1=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=8\\x=-1\end{matrix}\right.\)
→ S = \(\left\{8;-1\right\}\)
e, \(\frac{x-3}{2}=2-\frac{1-2x}{5}\)
⇌ 5( x - 3) = 20 - 2(1 - 2x)
⇌ 5x - 4x = 15 + 20 + 2
⇌ x = 37
→ S = \(\left\{37\right\}\)
g, \(\frac{3x+2}{2}+\frac{5-2x}{3}=\frac{11}{6}\)
⇌ 3(3x + 2) + 2(5 - 2x) = 11
⇌ 6x + 6 + 10 - 4x = 11
⇌ 2x = -5
⇌ x = \(-\frac{5}{2}\)
→ S = \(\left\{-\frac{5}{2}\right\}\)
h, \(\frac{x-2}{x+2}-\frac{3}{x-2}=\frac{9x-66}{x^2-4}\)
⇌ (x - 2)2 - 3(x - 2) = 9x - 66
⇌ x2 - 4x + 4 - 3x - 6 = 9x - 66
⇌ x2 -16 + 64 = 0
⇌ (x - 8)2 = 0
⇌ x - 8 = 0
⇌ x = 8
→ S = \(\left\{8\right\}\)
mik ko chép lại đề, mik làm luôn:
a) x - \(\frac{31}{36}=\frac{-13}{38}\)
x = \(\frac{-13}{18}+\frac{31}{36}\)
\(x=\frac{5}{36}\)
b)\(2-x-\frac{3}{7}=\frac{9}{-21}\)
\(\frac{11}{7}-x=\frac{3}{7}\)
x = \(\frac{11}{7}-\frac{3}{7}\)
x = 8/7
c) x + 3/11 = 23/44
x = 23/44 - 3/11
x = 1/4
d) \(\frac{1}{12}-x=\frac{-11}{9}\)
x = \(\frac{1}{12}+\frac{11}{9}\)
x = 47/36
e) \(x-\frac{2}{3}=\frac{-17}{3}\)
x= -17/3 + 2/3
x = -5
f) \(x-\frac{1}{2}=\frac{11}{4}.\frac{3}{11}\)
x - 1/2 = 3/4
x = 3/4 + 1/2
x = 5/4
g) \(2x+\frac{3}{8}=\frac{-21}{32}.\frac{4}{7}\)
2x + 3/8 = -3 / 8
2x = -3/8 - 3/8
2x = -9/8
x = -9/8.1/2
x = -9/16
h) x - \(\frac{x}{3}=\frac{3}{57}.\frac{19}{12}\)
x - \(\frac{x}{3}=\frac{1}{12}\)
x = \(\frac{1}{12}+\frac{x}{3}\)
x = \(\frac{1+4x}{12}\)
=> 12x = 1+4x
12x - 4x = 1
8x = 1
x = 1/8
\(a)A=\frac{7}{12}+\frac{11}{18}--\frac{5}{9}\)
\(A=\frac{21}{36}+\frac{22}{36}+\frac{5}{9}\)
\(A=\frac{21}{36}+\frac{22}{36}+\frac{20}{36}\)
\(A=\frac{63}{36}\)
\(A=\frac{7}{4}\)
\(b)B=6\frac{5}{7}+3\frac{3}{7}\)
\(B=\left(6+3\right)+\frac{5}{7}+\frac{3}{7}\)
\(B=9+\frac{8}{7}\)
\(B=\frac{63}{7}+\frac{8}{7}\)
\(B=\frac{71}{7}\)
Chúc bạn học tốt !!!
\(A=\frac{7}{12}+\frac{11}{18}+\frac{5}{9}\)
\(A=\frac{7}{3.4}+\frac{11}{2.3^2}+\frac{5}{3^2}\)
\(A=\frac{7.3}{2^2.3^2}+\frac{11.2}{2^2.3^2}+\frac{2^2.5}{2^2.3^3}\)
\(A=\frac{21+22+20}{4.9}\)
\(A=\frac{63}{4.9}\)
\(A=\frac{7}{4}\)
\(B=6\frac{5}{7}+3\frac{3}{7}\)
\(B=\frac{47}{7}+\frac{24}{7}\)
\(B=\frac{71}{7}\)
Tìm x nha!
Bài giải
\(\left(\frac{3}{5}-\frac{6}{7}\right)\text{ : }\frac{2x}{3}=-\frac{11}{18}\)
\(-\frac{9}{35}\text{ : }\frac{2x}{3}=-\frac{11}{18}\)
\(\frac{2x}{3}=\frac{-9}{35}\text{ : }\frac{-11}{18}\)
\(\frac{2x}{3}=\frac{-9}{35}\cdot\frac{18}{-11}\)
\(\frac{2x}{3}=\frac{162}{385}\)
\(385\cdot2x=162\cdot3\)
\(770x=486\)
\(x=\frac{243}{385}\)