bài 1 : thực hiện phép tính ( hợp lí )
a, (375 - 180) : 15
b, 678. (276+ 49)- 678 .(149 +76 )
bài 2:tính giá trị của biểu thức
12:\(\left\{390:\left[500-\left(125+35.7\right)\right]\right\}\)
bài 3 : tìm x thuộc N
a,2.\(3^x=54\)
b,\(3^2.3^x=81\)
c,\(\left(x-1\right)^3=8\)
bài 4; tính nhanh
A=100+98+96+....+2-97-95-....-1
\(\dfrac{-2}{3}.x+\dfrac{1}{5}=\dfrac{3}{10}\)
\(\dfrac{1}{3}+\dfrac{2}{3}:x=-7\)
\(60\%x=\dfrac{1}{3}.6\dfrac{1}{3}\)
\(\left(2x+\dfrac{3}{2}\right)^2-\dfrac{9}{25}=0\)
\(60\%x+0,4x+x:=2\)
\(\left(\dfrac{2}{3}-x\right):\dfrac{3}{4}=\dfrac{1}{5}\)
\(-2x-\dfrac{-3}{5}:\left(-0,5\right)^2=-1\dfrac{1}{4}\)
A=15.\(\left(\dfrac{3}{5}-\dfrac{2}{3}\right)+1\)
\(B=1-\dfrac{13}{9}:\dfrac{8}{19}+\dfrac{-11}{9}:\dfrac{8}{19}\)
\(C=\dfrac{-5}{7}.\dfrac{2}{11}+\dfrac{-5}{7}.\dfrac{9}{11}+1\dfrac{5}{7}\)
\(D=\dfrac{6}{7}+\dfrac{5}{8}:5-\dfrac{3}{16}.\left(-2\right)^2\)
tính giá trị của biểu thức
\(\dfrac{-5}{9}+1\dfrac{5}{9}\cdot\left(\dfrac{3}{4}-\dfrac{2}{5}\right):7^2\)
\(1\dfrac{13}{15}\cdot0,75-\left(\dfrac{104}{195}+25\%\right)\cdot\dfrac{24}{47}-3\dfrac{12}{13}:3\)
\(1\dfrac{13}{15}\cdot\left(0,5\right)^2\cdot3+\left(\dfrac{8}{15}+1\dfrac{19}{60}\right):1\dfrac{23}{24}\)