Câu hỏi:
\(\frac{23}{4}x=1\frac{89}{2}-67\)
1.\(\frac{-3}{5}.x=\frac{5}{6}\)
2.\(\frac{2}{4}:x=\frac{6}{8}\)
3.\(\frac{67}{89}.x=\frac{12}{13}\)
Ta có \(x.a=b\)
\(x=b:a\)
Do đó \(-\frac{3}{5}.x=\frac{5}{6}\)
\(x=\frac{5}{6}:\frac{-3}{5}\)
\(x=-\frac{1}{2}\)
Tương tự
2. \(x=\frac{6}{8}:\frac{2}{4}=\frac{3}{2}\)
Bạn tự làm câu 3
1.\(\frac{-3}{5}\).x=\(\frac{5}{6}\)
x=\(\frac{5}{6}\):\(\frac{-3}{5}\)
x=\(\frac{-25}{18}\)
2.\(\frac{2}{4}\):x=\(\frac{6}{8}\)
\(\frac{1}{2}\):x=\(\frac{3}{4}\)
x=\(\frac{1}{2}\):\(\frac{3}{4}\)
x=\(\frac{2}{3}\)
3.\(\frac{67}{89}\).x=\(\frac{12}{13}\)
x=\(\frac{12}{13}\):\(\frac{67}{89}\)
x=\(\frac{1068}{871}\)
K MIK NHÉ
Tính nhanh:
a) \(2.\frac{3}{7}+\left(\frac{2}{9}-1\frac{3}{7}\right)-\frac{5}{3}:\frac{1}{9}\)
b) \(\frac{-11}{23}.\frac{6}{7}+\frac{8}{7}.\frac{-11}{23}-\frac{1}{23}\)
c )\(\left(\frac{377}{-231}-\frac{123}{89}+\frac{34}{791}\right).\left(\frac{1}{6}-\frac{1}{8}-\frac{1}{24}\right)\)
d) \(19\frac{5}{8}:\frac{7}{12}-15\frac{1}{4}:\frac{7}{12}\)
e) \(\frac{2}{5}.\frac{1}{3}-\frac{2}{15}:\frac{1}{5}+\frac{3}{5}.\frac{1}{3}\)
a: \(=\dfrac{17}{7}+\dfrac{2}{9}-\dfrac{10}{7}-\dfrac{5}{3}\cdot9=1+\dfrac{2}{9}-15=-14+\dfrac{2}{9}=-\dfrac{126}{9}+\dfrac{2}{9}=-\dfrac{124}{9}\)
b: \(=\dfrac{-11}{23}\left(\dfrac{6}{7}+\dfrac{8}{7}\right)-\dfrac{1}{23}=\dfrac{-22}{23}-\dfrac{1}{23}=-1\)
c: \(=\left(\dfrac{377}{-231}-\dfrac{123}{89}+\dfrac{34}{791}\right)\cdot\dfrac{4-3-1}{24}=0\)
d: \(=\dfrac{12}{7}\left(19+\dfrac{5}{8}-15-\dfrac{1}{4}\right)=\dfrac{12}{7}\cdot\dfrac{35}{8}=\dfrac{15}{2}\)
So sánh : A = \(\frac{31}{23}+\left(\frac{7}{23}+\frac{8}{2}\right)\)và B = \(\left(\frac{1}{3}+\frac{12}{67}+\frac{13}{41}\right)-\left(\frac{79}{67}+\frac{28}{41}\right)\)
câu 1 : \(\frac{x+2}{42}+\frac{x+4}{22}=\frac{x+5}{23}+\frac{x+3}{43}\)
câu 2 : \(\frac{x-10}{20}+\frac{x-20}{10}+\frac{x-30}{5}=\frac{x-14}{4}\)
câu 1 : \(\frac{x+2}{42}+\frac{x+4}{22}=\frac{x+5}{23}+\frac{x+3}{43}\)
câu 2 : \(\frac{x-10}{20}+\frac{x-20}{10}+\frac{x-30}{5}=\frac{x-14}{4}\)
\(\frac{31}{23}-\left(\frac{7}{32}+\frac{8}{23}\right)+\left(\frac{1}{3}+\frac{12}{67}+\frac{13}{41}\right)-\left(\frac{79}{67}-\frac{28}{41}\right)\)
minh k biet xin loi ban nha!
minh k biet xin loi ban nha!
minh k biet xin loi ban nha!
minh k biet xin loi ban nha!
cho:
a) A= 2+\(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+....+\frac{1}{62}+\frac{1}{63}+\frac{1}{64}+\frac{1}{65}+\frac{1}{66}+\frac{1}{67}\)
chứng minh rằng A>5
b) B= \(\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{89^2}+\frac{1}{90^2}\)
chứng minh rằng \(\frac{40}{91}\)<B<1
Câu 1 :
Cho \(P=\left(1+\frac{\sqrt{x}}{x+1}\right):\left(\frac{1}{\sqrt{x}-1}-\frac{2\sqrt{x}}{x\sqrt{x}+\sqrt{x}-x-1}\right)\)
a) Rút gọn P
b) Tìm x để P < 2
Câu 2 :
Tính \(A=2x^3+2x^2+1\)
Với \(x=\frac{1}{3}\left(\sqrt[3]{\frac{23+\sqrt{513}}{4}+\sqrt[3]{\frac{23-\sqrt{513}}{4}-1}}\right)\)
Câu 1. Chỉ ra các phân số bằng nhau trong các phân số sau: \(\frac{6}{3};\frac{-8}{16};\frac{30}{15}\)
Câu 2 Thực hiện phép tính:
\(a;\frac{1}{4}+\frac{-3}{4}\) \(b;\frac{5}{6}-1\) \(c;\frac{-10}{27}.\frac{3}{-5}\) \(d;3\frac{1}{5}:2\frac{1}{3}\) \(e;\frac{-38}{35}+\frac{3}{35}\) \(g;\frac{67}{23}-\frac{44}{23}\) \(i;\frac{5}{6}+\left(2\frac{1}{3}-\frac{5}{6}\right)\) \(k;\frac{13}{23}.\frac{6}{17}+\frac{6}{17}.\frac{5}{46}\)