Lời giải:
Ta có:
\(\left(\frac{1}{2}-1\right)\left(\frac{1}{3}-1\right)...\left(\frac{1}{998}-1\right)\left(\frac{1}{999}-1\right)=\frac{1-2}{2}.\frac{1-3}{3}.....\frac{1-998}{998}.\frac{1-999}{999}\)
\(=\frac{-1}{2}.\frac{-2}{3}.\frac{-3}{4}....\frac{-997}{998}.\frac{-998}{999}\)
\(=\frac{(-1)(-2)(-3)....(-998)}{2.3.4...999}=\frac{1.2.3....998}{2.3.4...999}=\frac{1}{999}\)
A =\(\left(\frac{1}{2^2}-1\right)\).\(\left(\frac{1}{3^2}-1\right)\).\(\left(\frac{1}{4^2}-1\right)\).....................\(\left(\frac{1}{2015^2}-1\right)\).\(\left(\frac{1}{2016^2}-1\right)\)
B =\(\frac{-1}{2}\)
so sánh A và B
Giúp mk nha mk đang cần gấp lắm ! Cảm ơn trước!!!!!!!!!!!
tìm x:
(x-3)+2x2-6x=0
tính:
A=\(\left|x+\frac{3}{2}\right|-\left|x-1\right|+\left|x-\frac{3}{4}\right|\)
1) tìm x:
a) 3(x+2)-(x+2)=0
b) (x2+1).(x+2019)=0
c) (x-3)+2x2-6x=0
2) tính :
A=\(\left|x+\frac{3}{2}\right|-\left|x-1\right|+\left|x-\frac{3}{4}\right|\)
Tính nhanh
\(\left(\frac{1}{4.9}+\frac{1}{9.14}+\frac{1}{14.19}+...+\frac{1}{44.49}\right).\frac{1-3-5-7-...-49}{89}\)
\(\frac{5}{6}-\frac{23}{12}.x=\left(-\frac{1}{2}\right)^3\)
1)Tìm x, biết :
\(4.\left[3x-1\right]+\left[x\right]-2.\left[x-5\right]+7.\left[x-3\right]=12\)
\(\left[2\dfrac{1}{5}-x\right]+\left[x-\dfrac{1}{5}\right]+8\dfrac{1}{5}=1,2\)
\(3.\left[x+4\right]-\left[2.x+1\right]-5.\left[x-3\right]+\left[x-9\right]=5\)
\(2\left[x+3\dfrac{1}{2}\right]+\left[x\right]-3\dfrac{1}{2}=\left[2\dfrac{1}{5}-x\right]\)
Tìm giá trị lớn nhất của biểu thức: \(\frac{1}{\left(x-1^2\right)+2}\)
Tìm x biết
a,\(\frac{x-1}{x+5}\)=\(\frac{6}{7}\)
b,\(^{\left(x-\frac{1}{2^{ }}\right)^2}\)+\(\frac{2}{9}\)=\(\frac{2}{3}\)
Tính nhanh nếu có thể:
\(\left(5+\frac{1}{5}-\frac{2}{9}\right)\)-(2-\(\frac{1}{23}\)-\(2\frac{3}{35}\)+\(\frac{5}{6}\))-(8+\(\frac{2}{7}\)-\(\frac{1}{18}\))
Ccs bạn làm nhanh giúp mk nha. Mk cảm ơn nhìu
