\(B=\dfrac{120-\left(-0,5\right)\cdot\left(-40\right)\cdot\left(-5\right)\cdot\left(-0,2\right)\cdot20\cdot0\cdot25}{5+10+15+...+2015}\\ =\dfrac{120-0}{5+10+15+...+2015}\\ =\dfrac{120}{5+10+15+...+2015}\\ ĐặtA=5+10+15+2015\\ A=\left(2015+5\right)\cdot\left[\left(2015-5\right):5+1\right]:2\\ A=407030\\ VậyB=\dfrac{120}{407030}=\dfrac{6}{203515}\)
(5+10+15+...+1000)\(\left[\dfrac{2}{5}:0.5+2\left(-0.4\right)\right]:\left(\dfrac{1}{5}+\dfrac{1}{10}+\dfrac{1}{15}+...\dfrac{1}{1000}\right)\)
tính
a) \(\left[\dfrac{0.8\div\left(\dfrac{4}{5}\cdot1025\right)}{0.64-1}+\dfrac{\left(1.08-\dfrac{2}{25}\right)\div\dfrac{4}{7}}{\left(6\dfrac{5}{7}-3\dfrac{1}{4}\right)\cdot2\dfrac{2}{17}}+\left(1.2\cdot0.5\right)\div\dfrac{4}{5}\right]\)
b) \(\left(0.2\right)^{-3}\left[\left(-\dfrac{1}{5}\right)^{-2}\right]^{-1}+\left[\left(\dfrac{1}{2}\right)^{-3}\right]^{-2}\div\left(2^{-3}\right)^{-1}-\left(0.175\right)^{-2}\)
c) \(2+\dfrac{1}{1+\dfrac{1}{2+\dfrac{1}{1+\dfrac{1}{2}}}}\)
d) \(\dfrac{1}{90}-\dfrac{1}{72}-\dfrac{1}{56}-\dfrac{1}{42}-\dfrac{1}{3}\)
e) \(\left(\dfrac{1}{3}\right)^{-1}-\left(-\dfrac{6}{7}\right)^0+\left(\dfrac{1}{2}\right)^2\div2\)
f) \(\dfrac{\dfrac{1}{3}-\dfrac{1}{7}-\dfrac{1}{13}}{\dfrac{2}{3}-\dfrac{2}{7}-\dfrac{2}{13}}\cdot\dfrac{\dfrac{3}{4}-\dfrac{3}{16}-\dfrac{3}{64}-\dfrac{3}{256}}{1-\dfrac{1}{4}-\dfrac{1}{16}-\dfrac{1}{64}}+\dfrac{5}{8}\)
g) \(\dfrac{1}{-\left(2017\right)\left(-2015\right)}+\dfrac{1}{\left(-2015\right)\left(-2013\right)}+...+\dfrac{1}{\left(-3\right)\cdot\left(-1\right)}\)
h) \(\left(1-\dfrac{1}{1\cdot2}\right)+\left(1-\dfrac{1}{2\cdot3}+...+\left(1-\dfrac{1}{2017\cdot2018}\right)\right)\)
a \(\dfrac{3}{5}:\left(\dfrac{-1}{15}-\dfrac{1}{6}\right)+\dfrac{3}{5}:\left(\dfrac{-1}{3}-1\dfrac{1}{15}\right)\)
b\(\left\{\left[6,2:0,31-\dfrac{5}{6}.0,9.0,2+0,15\right]:0,2\right\}\left[\left(2+1\dfrac{4}{11}.0,22:0,1\right):\dfrac{1}{33}\right]\)
mong mọi người giúp đỡ
1)Tìm x biết: \(\dfrac{1}{2}-\left(\dfrac{1}{3}-\left(\dfrac{1}{4}-\left(\dfrac{1}{5}-x\right)\right)\right)=1\)
2) Tính B = \(\dfrac{2.5^{22}-9.5^{21}}{25^{10}}:\dfrac{5\left(3.7^{15}-19.7^{14}\right)}{7^{16}+3.7^{15}}\)
tính giá trị của mỗi biểu thức A,B,C,D rồi sắp xếp các kết quả tìm được theo thứ tự tăng dần:
A=\(\dfrac{5}{4}.\left(5-\dfrac{4}{3}\right).\left(-\dfrac{1}{11}\right)\) B=\(\dfrac{3}{4}:\left(-12\right).\left(-\dfrac{2}{3}\right)\)
C=\(\dfrac{5}{4}:\left(-15\right).\left(-\dfrac{2}{5}\right)\) D=\(\left(3\right).\left(\dfrac{2}{3}-\dfrac{5}{4}\right):\left(-7\right)\)
Tính bằng cách hợp lí :
A=\(\dfrac{5}{9}:\left(\dfrac{1}{11}-\dfrac{5}{2}\right)+\dfrac{5}{9}:\left(\dfrac{1}{15}-\dfrac{2}{3}\right)\)
B=\(\left(6-\dfrac{2}{3}+\dfrac{1}{2}\right)-\left(5+\dfrac{5}{3}-\dfrac{3}{2}\right)-\left(3-\dfrac{7}{3}+\dfrac{5}{2}\right)\)
1 tính
a, \(-\dfrac{2}{3}-\left(\dfrac{-2}{5}\right)-\dfrac{7}{10}\)
b, \(\dfrac{-5}{9}.\left(\dfrac{3}{10}-\dfrac{2}{5}\right)\)
c, \(\left(\dfrac{11}{24}:\dfrac{55}{36}\right).\dfrac{10}{3}\)
d, \(\left(\dfrac{1}{2}-1\right).\left(\dfrac{1}{3}-1\right)...\left(\dfrac{1}{2017}-1\right)\)
e,\(\left(\dfrac{2}{3}\right):\left(\dfrac{4}{9}\right)^{10}\)
f,\(\left(\dfrac{1}{7}\right)^7.7^7\)
g, \(\dfrac{\left(125\right)^5}{5^{15}}\)
2 tìm x, biết
a, \(\dfrac{-4}{7}-x=\dfrac{5}{7}\)
b, \(x:\left(\dfrac{-3}{8}\right)=\dfrac{1}{2}\)
c, \(\dfrac{-3}{5}+\dfrac{1}{4}:x=\dfrac{-2}{5}\)
d, \(\left(x-\dfrac{2}{5}\right).\left(x+\dfrac{3}{7}\right)=0\)
e, \(\left(x+1\right)^5=-32\)
f, \(x-\left(1,5-7\right)=0,35\)
3 tìm số tự nhiên n biết
a, \(3^n=81\)
b, \(2^n=16\)
c, \(2.2^n=16\)
d, \(2.8^n=128\)
5 so sánh
a, \(2^{333}\) và \(3^{222}\)
b, \(\left(\dfrac{-1}{16}\right)^{100}\) và \(\left(\dfrac{-1}{2}\right)^{400}\)
Tính nhanh :
\(A=\left(-\dfrac{5}{7}+\dfrac{8}{5}\right):\dfrac{91}{8}+\left(-\dfrac{2}{7}-\dfrac{3}{5}\right):\dfrac{91}{8}\)
\(B=\dfrac{13}{15}:\left(\dfrac{4}{5}-\dfrac{3}{7}\right)+\dfrac{13}{15}:\left(\dfrac{2}{5}-\dfrac{1}{9}\right)\)
(Gíup mình với )
tìm x;y
b \(\left|x-y\right|+\left|y+\dfrac{9}{25}=0\right|\)
c \(\left(\dfrac{1}{2}x-5\right)^{20}+\left(y^2-\dfrac{1}{4}\right)^{10}=0\)
a \(\left|\dfrac{1}{2}-\dfrac{1}{3}+x\right|=\dfrac{-1}{4}-y\)
d \(\left|x\left(x^2-\dfrac{5}{4}\right)\right|=x\) \(\left(x\ge0\right)\)
e \(x^2+\left(y-\dfrac{1}{10}\right)^4=0\)
