Tính
a. A= (2.872 x 0.25 + 2.166 : 0.1) x 0.05
b. B= (2-1/4+1/3-3/5)/(3-1/5-5/3) & viết kết quả dưới dạng hỗn số
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a, \(1+\dfrac{3}{4}=\dfrac{7}{4}\)
b, \(\dfrac{4}{5}-\dfrac{3}{8}=\dfrac{32-15}{40}=\dfrac{17}{40}\)
c, \(1:\dfrac{2}{3}=\dfrac{1.3}{2}=\dfrac{3}{2}\)
d, \(\dfrac{2}{5}.\dfrac{5}{2}=1\)
\(A=\dfrac{x^3}{9y^2}-\dfrac{1}{8}x^2y+\dfrac{2}{15}xy^2\\ B=\dfrac{2a-b}{a+1}-\dfrac{\left(a-1\right)^2}{b-2}\cdot\dfrac{\left(b-2\right)\left(b+2\right)}{\left(a-1\right)\left(a+1\right)}\\ B=\dfrac{2a-b}{a+1}-\dfrac{\left(a-1\right)\left(b+2\right)}{a+1}\\ B=\dfrac{2a-b-\left(a-1\right)\left(b+2\right)}{a+1}\\ B=\dfrac{2a-b-ab-2a+b+2}{a+1}=\dfrac{2-ab}{a+1}\)
\(\dfrac{3}{2}x+\dfrac{3}{7}=-\dfrac{4}{5}\)
\(\Leftrightarrow\dfrac{3}{2}x=-\dfrac{43}{35}\)
\(\Leftrightarrow x=-\dfrac{86}{105}\)
Vậy \(x=-\dfrac{86}{105}\)
\(-\dfrac{11}{12}x+0,25=\dfrac{5}{6}\)
\(\Leftrightarrow-\dfrac{11}{12}x+\dfrac{1}{4}=\dfrac{5}{6}\)
\(\Leftrightarrow-\dfrac{11}{12}x=\dfrac{7}{12}\)
\(\Leftrightarrow x=-\dfrac{7}{11}\)
Vậy \(x=-\dfrac{7}{11}\)
\(\left(x-2\right)^2=1\)
\(\Leftrightarrow\left(x-2\right)^2-1=0\)
\(\Leftrightarrow\left(x-2-1\right)\left(x-2+1\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left(x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-3=0\\x-1=0\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=1\end{matrix}\right.\)
Vậy x = {3; 1}\(\left(2x-1\right)^3=-8\)
\(\Leftrightarrow2x-1=-2\)
\(\Leftrightarrow2x=-1\)
\(\Leftrightarrow x=-\dfrac{1}{2}\)
Vậy \(x=-\dfrac{1}{2}\)
(x - 2)2 = 1
<=>\(\left[{}\begin{matrix}x-2=1\\x-2=-1\end{matrix}\right.< =>\left[{}\begin{matrix}x=3\\x=1\end{matrix}\right.\)
Vậy x = 3; 1
(2x - 1)3 = -8
<=> 2x - 1 = -2
<=> 2x = -1
<=> x = \(\dfrac{-1}{2}\)
Vậy x = \(\dfrac{-1}{2}\)
a) 3/7 + 3/4 - 1/2 =33/28-1/2=19/28
b) 6/11 + 2/9 x 12 =6/11+8/3=106/33
c) 5/7 - 8/5 : 4 =5/7-2/5=11/35
a) 3/7 + 3/4 - 1/2 = \(\dfrac{12}{28}+\dfrac{21}{28}-\dfrac{14}{28}=\dfrac{19}{28}\)
b) 6/11 + 2/9 x 12 = \(\dfrac{6}{11}+\dfrac{8}{3}=\dfrac{18}{33}+\dfrac{88}{33}=\dfrac{106}{33}\)
c) 5/7 - 8/5 : 4 = \(\dfrac{5}{7}-\dfrac{2}{5}=\dfrac{25}{35}-\dfrac{14}{35}=\dfrac{11}{35}\)
a)A=1.1189
b)B=1/21/68