a.Áp dụng t/c dãy tỉ số bằng nhau:
\(\dfrac{42+x}{30+x}=\dfrac{6}{7}\)
<=> 7(42+x) = 6(30+x)
<=> 294 + 7x = 180 + 6x
<=> x = -114
b.Áp dụng t/c dãy tỉ số bằng nhau:
\(\dfrac{x+15}{8}=\dfrac{x-12}{9}\)
<=> 9(x+15) = 8(x-12)
<=> 9x + 135 = 8x - 96
<=> x = -231
Tìm x biết rằng:
\(\dfrac{-5}{6}-x=\dfrac{7}{12}+\dfrac{-2}{3}\)
b) Tìm tập hợp các số của x biết rằng:
\(\dfrac{-7}{15}+\dfrac{4}{30}+\dfrac{12}{45}< _-\dfrac{x}{15} < _-\dfrac{3}{5}+ \dfrac{4}{15}+\dfrac{-2}{5}\)
Tìm x \(\in\) Z biết;
a) \(\dfrac{x}{15}=\dfrac{4}{y}=\dfrac{-2}{5}\)
b) \(\dfrac{x-3}{4}=\dfrac{15}{20}\)
c) \(\dfrac{-5}{9}+\dfrac{-8}{15}+\dfrac{22}{-9}+\dfrac{-7}{15}< x\le\dfrac{-1}{3}+\dfrac{-1}{4}+\dfrac{-5}{12}\)
Tìm x biết:
\(\dfrac{x}{5}=\dfrac{-19}{30}+\dfrac{5}{6}\)
\(\dfrac{6}{7}+\dfrac{5}{7}:x=\dfrac{8}{9}\)
Tìm x biết
\(\dfrac{x-1}{12}+\dfrac{x-1}{20}+\dfrac{x-1}{30}+\dfrac{x-1}{42}+\dfrac{x-1}{56}+\dfrac{x-1}{72}=\dfrac{16}{9}\)
Help me!! Mk đang cần gấp
\(\dfrac{x-1}{12}+\dfrac{x-1}{20}+\dfrac{x-1}{30}+\dfrac{x-1}{42}+\dfrac{x-1}{56}+\dfrac{x-1}{72}=\dfrac{16}{9}\)
Tìm x biết :
\(2x+\dfrac{7}{6}+\dfrac{13}{12}+\dfrac{21}{20}+\dfrac{31}{30}+\dfrac{43}{42}+\dfrac{57}{56}+\dfrac{73}{72}+\dfrac{91}{90}=10\)
Bài 1; Tính
a)\(\left(\dfrac{5}{18}-\dfrac{7}{24}+\dfrac{1}{9}\right):\dfrac{7}{18}\)
b)\(\left(\dfrac{7}{20}-\dfrac{5}{16}+\dfrac{3}{40}\right):\left(\dfrac{4}{15}-\dfrac{3}{10}+\dfrac{1}{12}\right)\)
Bài 2:Tìm x
a)\(\dfrac{3}{10}-x=\dfrac{5}{6}-\dfrac{2}{15}\)
b)\(\dfrac{-5}{8}+x=\dfrac{4}{9}-\dfrac{7}{1}\)
c)\(\dfrac{2}{x-3}=\dfrac{x-3}{18}\)
Giúp mk zới m.n mk gấp lắm mk tick cho
Bài 1: Tính hợp lý:
a. 1152 - (374 + 1152) + (374 - 65)
b. \(\dfrac{7}{12}\) + \(\dfrac{5}{6}\) + \(\dfrac{1}{4}\) - \(\dfrac{3}{7}\) - \(\dfrac{5}{12}\)
c. \(\dfrac{11.3^{22}.3^7-9^{15}}{\left(2.3^{14}\right)^2}\)
d, \(\dfrac{3}{2^2}\) . \(\dfrac{8}{3^2}\) . \(\dfrac{15}{4^2}\) ... \(\dfrac{899}{30^2}\)
Bài 2: Tìm x biết:
a, 2x + 2x+1 + 2x+2 + 2 x+3 = 480
b, \(\left(\dfrac{1}{2}+\dfrac{1}{3}+...+\dfrac{1}{2012}+\dfrac{1}{2013}\right)\) . x = \(\dfrac{2012}{1}+\dfrac{2011}{2}+\dfrac{2010}{3}+...+\dfrac{2}{2011}+\dfrac{1}{2012}.\)
Bài 1: Tìm x, biết:
a, \(\left(x+\dfrac{1}{4}-\dfrac{1}{3}\right):\left(2+\dfrac{1}{6}-\dfrac{1}{4}\right)=\dfrac{7}{46}\)
b, \(\dfrac{13}{15}-\left(\dfrac{13}{21}+x\right).\dfrac{7}{12}=\dfrac{7}{10}\)
Bài 2: Thực hiện phép tính:
a, \(\left(2\dfrac{5}{6}+1\dfrac{4}{9}\right):\left(10\dfrac{1}{12}-9\dfrac{1}{2}\right)\)
b, 1\(\dfrac{5}{18}-\dfrac{5}{18}.\left(\dfrac{1}{15}+1\dfrac{1}{12}\right)\)
c, \(-\dfrac{1}{7}.\left(9\dfrac{1}{2}-8,75\right):\dfrac{2}{7}+0,625:1\dfrac{2}{3}\)