a)\(x+\dfrac{1}{2}=\dfrac{6}{4}\)

\(x=\dfrac{3}{2}-\dfrac{1}{2}\)

\(x=1\)

Vậy\(x=1\)

b)\(x^4.3^5=27^3\)

\(x^4.3^5=\left(3^3\right)^3\)

\(x^4.3^5=3^9\)

\(x^4=3^9\div3^5\)

\(x^4=3^4\)

\(\Rightarrow x=4\)

Vậy \(x=4\)

c)\(\dfrac{8}{3}\left(\dfrac{5}{24}-x\right)=\dfrac{-1}{3}\)

\(\dfrac{5}{24}-x=\dfrac{-1}{3}\div\dfrac{8}{3}\)

\(\dfrac{5}{24}-x=\dfrac{-1}{3}.\dfrac{3}{8}\)

\(\dfrac{5}{24}-x=\dfrac{-1}{8}\)

\(x=\dfrac{5}{24}+\dfrac{1}{8}\)

\(x=\dfrac{5+3}{24}\)

\(x=\dfrac{1}{3}\)

Vậy \(x=\dfrac{1}{3}\)

a)\(\dfrac{5}{4}\)\(-\left(\dfrac{1}{2}\right)^2\)

=\(\dfrac{5}{4}-\dfrac{1}{4}\)

=\(1\)

b)\(\dfrac{2}{3}.\dfrac{-3}{2}+\dfrac{-7}{2}.\dfrac{2}{3}\)

=\(\dfrac{2}{3}\left(\dfrac{-3}{2}+\dfrac{-7}{2}\right)\)

=\(\dfrac{2}{3}.\left(-5\right)\)

=\(\dfrac{-10}{3}\)

c)\(\left(\dfrac{1}{5}+\dfrac{4}{13}\right)+\left(\dfrac{-2}{5}+\dfrac{7}{13}\right)-\left(\dfrac{4}{5}-\dfrac{2}{13}\right)\)

=\(\dfrac{1}{5}+\dfrac{4}{13}-\dfrac{2}{5}+\dfrac{7}{13}-\dfrac{4}{5}+\dfrac{2}{13}\)

=\(\dfrac{1}{5}-\dfrac{2}{5}-\dfrac{4}{5}+\dfrac{4}{13}+\dfrac{7}{13}+\dfrac{2}{13}\)

=\(-1+1\)

=\(0\)

10  số lẻ

là số lẻ

nếu lớn nhất là 99998

nếu bé nhất là 11110

Vì proton = electron nên proton = 19 hạt

Số hạt neutron là:

58-19-19=20(hạt)

Khối lượng nguyên tử X:

19+20=39(amu)

Vậy nguyên tử X có:

Số hạt proton:19 hạt

           electron:19 hạt

            neutron:20 hạt

Khối lượng nguyên tử X:39 amu

B

a^3+b^3=(a^2-ab+b^2)(a+b)

=36