Áp dụng dãy tỉ số bằng nhau ta có :
\(\frac{x^2}{9}=\frac{y^2}{16}=\frac{x^2+y^2}{9+16}=\frac{100}{25}=4\)
=> \(x^2=4.9=36\)
=> x = 6 hoặc x = -6
=> \(y^2=4.16=64\)
=> y = 8 hoặc y = -8
Tim x,y,z :
a) x=y:2,\(\frac{y}{4}=\frac{z}{5}\)va 2x+2y-z-7=0
b)\(\frac{1}{2}x=\frac{2}{3}y=\frac{3}{4}z\)va x-y=15
c)\(\frac{x}{y}=\frac{2}{3}\), \(\frac{x}{z}=\frac{1}{2}\)va \(x^3\)- xyz=-16
tim x,y biết: \(\frac{x}{3}+\frac{y}{4}\)va \(x^2+y^2=100\)
Tim x,y,z biet
a,5x= 8y= 20z va x-y-z = 3
b,\(\frac{6}{11}x=\frac{9}{2}y=\frac{18}{5}z\)va -x+y+z =120
c,\(\frac{x}{12}=\frac{y}{9}=\frac{z}{5}\)va x . y . z =20
d,\(\frac{x}{5}=\frac{y}{7}=\frac{z}{3}\)va \(^{x^2+y^2-z^2}\)=585
Tim x.
x^2/9=y^2/16 va x^2+y^2=100
x/19=y/21va 2x-y=34
chuc mung nam moi . happy new year 2016
C, CHO 7X=3Y VA X -Y =16
D, CHO \(\frac{X}{2}=\frac{Y}{3}=\frac{Z}{4}\)VA A +2B -3C = -20
E, CHO X :Y :Z =7:4:2 VA X- 3Z =9
F,CHO \(\frac{X}{Y}=\frac{7}{10};\frac{Y}{Z}=\frac{10}{3}\)VA X+Y+Z=120
G,CHO 3X=4Y=5Z VA X-Y-Z=-42
Tìm x, y biết : \(\frac{x^2}{9}=\frac{y}{16}\) và x2 + y2 = 100
TIM X, Y ,Z , BIET :\(\frac{x-2}{6}=\frac{y+3}{9}=\frac{z-7}{10}\)va \(x+y+z=106\)
Tim cac so x,y,z biet \(\frac{x}{5}=\frac{y}{7}=\frac{z}{3}\)va x2 va y2 va z2
Tìm x, y biết : \(\frac{x^2}{9}=\frac{y^2}{16}\) và x2 + y2 = 100
