Question

\(a.\) Tìm các số x,y,z biết rằng: 3x = 4y, 5y = 6z và xyz = 30

b. Tìm x biết: \(\left|x-\dfrac{1}{2}\right|+\dfrac{3}{4}=\left|-1.6+\dfrac{3}{5}\right|\)

Answer 1

ta có :3x=4y,5y=6z

=>\(\dfrac{x}{4}\)=\(\dfrac{y}{3}\); \(\dfrac{y}{6}\)=\(\dfrac{z}{5}\)

=> \(\dfrac{x}{8}\)=\(\dfrac{y}{6}\); \(\dfrac{y}{6}\)=\(\dfrac{z}{5}\)

=> \(\dfrac{x}{8}\)=\(\dfrac{y}{6}\)=\(\dfrac{z}{5}\)

Đặt \(\dfrac{x}{8}\)=\(\dfrac{y}{6}\)=\(\dfrac{z}{5}\)=k

=> x=8k ; y=6k ; z=5k

=> 8k.6k.5k=30

=> 240k³ =30

=>k³ =8

=>k=2

=> x=8.2=16 ; y=6.2=12 ; x =5.2=10

Answer 2

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