bài 2:
a: \(-\dfrac{3}{2}-2x=1\)
=>\(2x=-\dfrac{3}{2}-1=-\dfrac{5}{2}\)
=>\(x=-\dfrac{5}{2}:2=-\dfrac{5}{4}\)
b: \(-\dfrac{1}{8}\left(x-1\right)^3-0,8=20\%\)
=>\(-\dfrac{1}{8}\left(x-1\right)^3=0,2+0,8=1\)
=>\(\left(x-1\right)^3=-8\)
=>x-1=-2
=>x=-1
c: \(3,5x-\dfrac{3}{4}-x=\left(-0,5\right)^2\)
=>2,5x-0,75=0,25
=>2,5x=1
=>x=1:2,5=0,4
d: 16x5=x
=>\(16x^5-x=0\)
=>\(x\left(16x^4-1\right)=0\)
=>\(\left[{}\begin{matrix}x=0\\16x^4-1=0\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}x=0\\x^4=\dfrac{1}{16}\end{matrix}\right.\)
=>\(\left[{}\begin{matrix}x=0\\x=\dfrac{1}{2}\\x=-\dfrac{1}{2}\end{matrix}\right.\)
bài 1:
a: \(\dfrac{1}{2}-25\%+1=\dfrac{3}{2}-\dfrac{1}{4}=\dfrac{6}{4}-\dfrac{1}{4}=\dfrac{5}{4}\)
b: \(\dfrac{4}{9}\cdot2,25-\left(-\dfrac{2}{3}\right)^2\cdot0,25-\dfrac{4}{-9}\)
\(=\dfrac{4}{9}\cdot\dfrac{9}{4}+\dfrac{4}{9}-\dfrac{4}{9}\cdot\dfrac{1}{4}\)
\(=1+\dfrac{4}{9}-\dfrac{1}{9}=1+\dfrac{3}{9}=\dfrac{4}{3}\)
c: \(\left(3\dfrac{2}{5}-\dfrac{5}{7}-\dfrac{-3}{11}\right)-\left(\dfrac{2}{7}-1\dfrac{3}{5}-\dfrac{8}{11}\right)\)
\(=3+\dfrac{2}{5}-\dfrac{5}{7}+\dfrac{3}{11}-\dfrac{2}{7}+1+\dfrac{3}{5}+\dfrac{8}{11}\)
\(=\left(3+1\right)+\left(\dfrac{2}{5}+\dfrac{3}{5}\right)+\left(\dfrac{3}{11}+\dfrac{8}{11}\right)+\left(-\dfrac{5}{7}-\dfrac{2}{7}\right)\)
\(=4+1+1-1=5\)
d: \(\dfrac{1}{3}-1,2:\left(-1,5-40\%\right)\)
\(=\dfrac{1}{3}-1,2:\left(-1,5-0,4\right)\)
\(=\dfrac{1}{3}+\dfrac{12}{19}=\dfrac{19+36}{57}=\dfrac{55}{57}\)
