A =15/x+2 + 14/x+2 = 29/x+2
b) x+2 là U(29) = { -1;1;-29;29}
=> x ={ -3;-1;-31;27}
\(A=\frac{1}{15}.\frac{225}{x+2}+\frac{3}{14}.\frac{196}{3x+6}=\frac{225}{\left(x+2\right)15}+\frac{196.3}{\left(3x+6\right)14}=\frac{15.15}{\left(x+2\right)15}+\frac{14.14.3}{3\left(x+2\right)14}=\frac{15}{x+2}+\frac{14}{x+2}=\frac{39}{x+2}\)