84 : 4 + 27 : 21 + 5
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a; \(\dfrac{9}{27}\) + \(\dfrac{7}{-49}\)
= \(\dfrac{1}{3}\) - \(\dfrac{1}{7}\)
= \(\dfrac{7}{21}\) - \(\dfrac{3}{21}\)
= \(\dfrac{4}{21}\)
b; - \(\dfrac{12}{10}\) + \(\dfrac{-25}{30}\)
= - \(\dfrac{6}{5}\) - \(\dfrac{5}{6}\)
= -\(\dfrac{36}{30}\) - \(\dfrac{25}{30}\)
= \(\dfrac{-61}{30}\)
c; \(\dfrac{-20}{35}\) + \(\dfrac{-16}{-24}\)
= - \(\dfrac{4}{7}\) + \(\dfrac{2}{3}\)
= - \(\dfrac{12}{21}\) + \(\dfrac{14}{21}\)
= \(\dfrac{2}{21}\)
d; - \(\dfrac{21}{77}\) + \(\dfrac{10}{-35}\)
= - \(\dfrac{3}{11}\) - \(\dfrac{2}{7}\)
= - \(\dfrac{21}{77}\) - \(\dfrac{22}{77}\)
= - \(\dfrac{43}{77}\)
a: Các phân số tối giản là 4/9; 17/13
b: Các phân số bằng 4/7 là 12/21; 36/63; 48/84;
\(1)x+23-19+48=-50\)
\(\Rightarrow x+23-19=-50-48\)
\(\Rightarrow x+23-19=-98\)
\(\Rightarrow x+23=-98+19\)
\(\Rightarrow x+23=-79\)
\(\Rightarrow x=-79-23=-102\)
\(2)3x-27-21+84=12\)
\(\Rightarrow3x-27-21=12-84\)
\(\Rightarrow3x-27-21=12+(-84)\)
\(\Rightarrow3x-27-21=-72\)
\(\Rightarrow3x-27=-72+21\)
\(\Rightarrow3x-27=-51\)
\(\Rightarrow3x=-51+27\)
\(\Rightarrow3x=-24\)
\(\Rightarrow x=-24\div3=-8\)
Chúc bạn học tốt ~
\(a,x+23-19+48=-50\)
\(\Rightarrow x=-50-23+19-48\)
\(\Rightarrow x=-102\)
a: =>-3x=1/21*84/5=4/5
=>x=-4/5:3=-4/15
b: =>-1/6x=-3/4-1/5=-19/20
=>x=19/20:1/6=19/20*6=57/10
2/14+3/21=1/7+1/7=2/7
4/5+15/25=4/5+3/5=7/5
21/27+4/9=7/9+4/9=11/9
84 : 4 + 27 : 21 + 5
= 21 + \(\frac{9}{7}\)+ 5
= \(\frac{156}{7}\) + 5
= \(\frac{191}{7}\)
a) 71-(33+x)=26
b) 135-5(x+4)=35
c) 25+(x-8)=106
d) 5x +x=39-33:27
e) 4 mũ x=64
f) 2 mũ x : 2 mũ 5=1