\(a,\left(2-x\right)\left(\dfrac{4}{5}-x\right)< 0\)
=>Trong 2 số phải có 1 số âm và 1 số dương
Mà \(2-x>\dfrac{4}{5}-x\)
=>\(\dfrac{4}{5}< x< 2\)
Vậy...
Tìm x ạ
b) \(\left|\dfrac{3}{4}x-\dfrac{3}{4}\right|-\dfrac{3}{4}=\left|\dfrac{-3}{4}\right|\)
c) \(\left|x+\dfrac{3}{5}\right|-\left|x-\dfrac{7}{3}\right|=0\)
Tìm \(x\in Q\), biết rằng :
a) \(\dfrac{11}{12}-\left(\dfrac{2}{5}+x\right)=\dfrac{2}{3}\)
b) \(2x\left(x-\dfrac{1}{7}\right)=0\)
c) \(\dfrac{3}{4}+\dfrac{1}{4}:x=\dfrac{2}{5}\)
Câu 1: Tim x, y biet:
a) \(2.x-\dfrac{5}{4}=\dfrac{20}{15}\)
b) \(\left(x+\dfrac{1}{3}\right)^3=\left(\dfrac{-1}{8}\right)\)
Câu 2: Tim cac so a,b biet:
\(\dfrac{a}{2}=\dfrac{b}{3}\) va \(a+b=-15\)
Câu 3: Tim x \(\in\) Q biet:
\(\left(x+1\right)\left(x-2\right)< 0\)
Câu 4: Thuc hien phep tinh:
\(B=\left(\dfrac{3}{7}\right)^{21}:\left(\dfrac{9}{49}\right)^9\)
Tìm \(x\in Q\), biết rằng:
a) \(\dfrac{11}{12}-\left(\dfrac{2}{5}+x\right)=\dfrac{2}{3}\)
b) \(2x.\left(x-\dfrac{1}{7}\right)=0\)
c) \(\dfrac{3}{4}+\dfrac{1}{4}:x=\dfrac{2}{5}\)
Bài 1: Tính
\(\dfrac{1}{2}.\dfrac{1}{-3}+\dfrac{1}{-3}.\dfrac{1}{4}+\dfrac{1}{4}.\dfrac{1}{-5}+\dfrac{1}{-5}.\dfrac{1}{6}\)
Bài 2: Tìm x ∈ Q:
\(\left(x-\dfrac{4}{7}\right).\left(x+\dfrac{1}{2}\right)>0\)
Tìm x:
\(\dfrac{3}{\left(x+2\right)\left(x+5\right)}\)\(+\dfrac{5}{\left(x+5\right)\left(x+10\right)}\)\(+\dfrac{7}{\left(x+10\right)\left(x+17\right)}\)\(=\dfrac{x}{\left(x+2\right)\left(x+17\right)}\)
Tìm \(x\in\mathbb{Q}\), biết :
a) \(\left(x+1\right)\left(x-2\right)< 0\)
b) \(\left(x-2\right)\left(x+\dfrac{2}{3}\right)>0\)
a) Cho x=3,7. So sánh:
A = [x] + [x+\(\dfrac{1}{5}\)] + [x+\(\dfrac{2}{5}\)] + [x+\(\dfrac{3}{5}\)] + [x+\(\dfrac{4}{5}\)] và B=[5x]
b)Tính [\(\dfrac{100}{3}\)] + [\(\dfrac{100}{3^2}\)] + [\(\dfrac{100}{3^3}\)] + [\(\dfrac{100}{3^4}\)]
c) Tính \(\left[\dfrac{50}{2}\right]+\left[\dfrac{50}{2^2}\right]+\left[\dfrac{50}{2^3}\right]+\left[\dfrac{50}{2^4}\right]+\left[\dfrac{50}{2^5}\right]\)
Tìm x :
\(7-\dfrac{1}{2}.\left(2x-5\right)-\dfrac{2}{3}\left(3x+1\right)=5\)