Question

cho a:b:c=3:4:5 gia tri bieu thuc \(\frac{5a^2+2b^2-c^2}{2a^2+3b^2-2c^2}\) la........

Answer 1

Ta có :

a:b:c=3:4:5

\(\Rightarrow\frac{a}{3}=\frac{b}{4}=\frac{c}{5}\)

Đặt \(\frac{a}{3}=\frac{b}{4}=\frac{c}{5}=k\)

\(\Rightarrow\begin{cases}a=3k\\b=4k\\c=5k\end{cases}\)

Thay vào biểu thức ta được :

\(\frac{5a^2+2b^2-c^2}{2a^2+3b^2-2c^2}=\frac{5.9.k^2+2.16.k^2-25.k^2}{2.9.k^2+3.16.k^2-2.25.k^2}=\frac{k^2\left(45+32-25\right)}{k^2\left(18+48-50\right)}=\frac{52}{16}=\frac{13}{4}\)

Answer 2

13/4

Answer 3

β♂ λ

Answer 4

13/4

Answer 5

\(\frac{13}{4}\)

Answer 6

\(\dfrac{13}{4}\)