Question

[o0o nghịch ngợm o0o]

a, \(\frac{x}{y}=\frac{7}{20};\)\(\frac{y}{z}=\frac{7}{3}\)và x- y + z = -155

b, \(\frac{x}{5}=\frac{y}{4}=\frac{z}{-6}\)và x³ + 3z³ = -14121

c, 4x = 5y ; 3y = 2z và x²  - 2y² - 3z³ = -460

mk đang gấp , mn giúp mk với nha

Answer 1

[I don't need you]

b)ta có: \(\frac{x}{5}=\frac{y}{4}=\frac{z}{-6}\Rightarrow\frac{x^3}{125}=\frac{y^3}{64}=\frac{z^3}{-216}=\frac{x^3}{125}=\frac{y^3}{64}=\frac{3z^3}{-648}\)

ADTCDTSBN

có: \(\frac{x^3}{125}=\frac{3z^3}{-648}=\frac{x^3+3z^3}{125+\left(-648\right)}=\frac{-14121}{-523}=27\)

=> x³/125 = 27 => x³ = 3 375 => x = 15

y³/64 = 27 => y³ = 1 728 => y = 12

z³/-216 =27 => z³ = -5 832 => z³ = -18

KL:...

câu c thì mk ko bk! sr bn nha!

Answer 2

[I don't need you]

a) ta có: \(\frac{x}{y}=\frac{7}{20}\Rightarrow x20=y7\Rightarrow\frac{x}{7}=\frac{y}{20}\Rightarrow\frac{x}{49}=\frac{y}{140}\)

\(\frac{y}{z}=\frac{7}{3}\Rightarrow y3=z7\Rightarrow\frac{y}{7}=\frac{z}{3}\Rightarrow\frac{y}{140}=\frac{z}{60}\)

\(\Rightarrow\frac{x}{49}=\frac{y}{140}=\frac{z}{60}\)

ADTCDTSBN

có: \(\frac{x}{49}=\frac{y}{140}=\frac{z}{60}=\frac{x-y+z}{49-140+60}=\frac{-155}{-31}=5\)

=> x/49 = 5 => x = 245

y/140 = 5 => y = 700

z/60 = 5 => z = 300

KL:...