Bạn tham khảo nha:
* \(\dfrac{a}{2}=\dfrac{b}{3}=\dfrac{c}{4}=\dfrac{a}{2}=\dfrac{2b}{6}=\dfrac{c}{4}=\dfrac{a+2b+c}{2+6+4}=\dfrac{a+2b+c}{12}\) (1)
* \(\dfrac{a}{2}=\dfrac{b}{3}=\dfrac{c}{4}=\dfrac{a+b-c}{2+3-4}=\dfrac{a+b-c}{2+3-4}=\dfrac{a+b-c}{1}\) (2)
(1)(2)=> \(\dfrac{a+2b+c}{12}=\dfrac{a+b-c}{1}=\dfrac{a+2b-c}{a+b-c}=\dfrac{12}{1}=12\)
=> H = 12.
Kết quả: Chọn C.
Chúc bạn học tốt :D