Vế trái nha bạn.

\(\dfrac{a}{c}=\dfrac{c}{b}\Rightarrow ab=c^2\)

\(a,VT=\dfrac{a^2+c^2}{b^2+c^2}=\dfrac{a^2+ab}{b^2+ab}=\dfrac{a\left(a+b\right)}{b\left(b+a\right)}=\dfrac{a}{b}=VP\left(dpcm\right)\)

\(c,VT=\dfrac{b^2-a^2}{a^2+c^2}=\dfrac{\left(b-a\right)\left(b+a\right)}{a^2+ab}=\dfrac{\left(b-a\right)\left(a+b\right)}{a\left(a+b\right)}=\dfrac{b-a}{a}=VP\left(dpcm\right)\)

\(P=\dfrac{2sin\alpha-3cos\alpha}{3sin\alpha+2cos\alpha}\\ =\dfrac{\dfrac{2sin\alpha}{cos\alpha}-\dfrac{3cos\alpha}{cos\alpha}}{\dfrac{3sin\alpha}{cos\alpha}+\dfrac{2cos\alpha}{cos\alpha}}\\ =\dfrac{2tan\alpha-3}{3tan\alpha+2}=\dfrac{2.3-3}{3.3+2}=\dfrac{3}{11}\)

chê =))

nghệ z :))

là tăm tối đó 

U Minh à :)

thôi ngu lắm

thần đồng thì không, thần đần thì có nè =))