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a) đáp án là 15/14 hoặc 1 1/4
b) đáp án là 27/5 hoặc 5 2/5. Hok tốt!!:)
\(A=\frac{3}{7}+\frac{4}{9}+\frac{4}{7}+\frac{7}{11}\)
\(A=1+\frac{4}{9}+\frac{7}{11}\)
\(A==\frac{76}{33}\)
\(B=\frac{1}{8}+\frac{1}{12}+\frac{3}{8}+\frac{5}{12}\)
\(B=\frac{1}{2}+\frac{1}{2}\)
\(B=\frac{1}{4}\)
a) 1+2+3+4+5+6+7+8+9
= (1+9)+(2+8)+(3+7)+(4+6)+5
= 10+10+10+10=5
= 45
b) 19+28+37+46+81+72+63+54
= (19+81)+(28+72)+(46+54)+(63+37)
= 100+100+100+100
= 400
A = (2 + 22) + (23 + 24 ) +…(2199 + 2200)
A = 6 + 22 (2 + 22 ) +… + 2198 (2 + 22)
A = 6 + 22 (6 ) +… + 2198 (6)
A = 6(1 + 22 +… + 2198)
Vậy A chia hết cho 6
a) \(\left(\frac{2}{7}+\frac{3}{8}+\frac{12}{7}+\frac{5}{8}\right).\frac{19}{36}\)
\(=\left\{\left(\frac{2}{7}+\frac{12}{7}\right)+\left(\frac{3}{8}+\frac{5}{8}\right)\right\}.\frac{19}{36}\)
\(=\left(\frac{14}{7}+\frac{8}{8}\right).\frac{19}{36}\)
\(=\left(2+1\right).\frac{19}{36}\)
\(3.\frac{19}{36}=\frac{19}{12}\)
A) \(\frac{7}{8}-\frac{5}{12}=\frac{84}{96}-\frac{40}{96}=\frac{44}{96}=\frac{11}{24}\)
B)\(\frac{8}{15}-\frac{2}{5}=\frac{8}{15}-\frac{6}{15}=\frac{2}{15}\)
C)\(\frac{5}{6}-\frac{3}{10}=\frac{50}{60}-\frac{18}{60}=\frac{32}{60}=\frac{8}{15}\)
D)\(\frac{7}{10}-\frac{1}{5}=\frac{7}{10}-\frac{2}{10}=\frac{5}{10}=\frac{1}{2}\)
2)A)\(\frac{5}{10}-\frac{2}{15}=\frac{1}{2}-\frac{2}{15}=\frac{15}{30}-\frac{4}{30}=\frac{11}{30}\)
B)\(\frac{5}{20}-\frac{1}{6}=\frac{1}{4}-\frac{1}{6}=\frac{6}{24}-\frac{4}{24}=\frac{2}{24}=\frac{1}{12}\)
C)\(\frac{6}{18}-\frac{6}{24}=\frac{1}{3}-\frac{1}{4}=\frac{4}{12}-\frac{3}{12}=\frac{1}{12}\)
D)\(\frac{5}{9}-\frac{3}{12}=\frac{5}{9}-\frac{1}{4}=\frac{20}{36}-\frac{9}{36}=\frac{11}{36}\)
Chúc bạn học tốt
\(\dfrac{12}{a}-\dfrac{54}{7}+\left[5+8-9\times1\div3\right]\)
\(\dfrac{12}{a}-\dfrac{54}{7}+\)14
\(\dfrac{12}{1}-\dfrac{54}{7}+14\)
\(\dfrac{19}{4}+14\)
\(\dfrac{75}{4}\)
Chúc bạn học tốt.
ok