Question

ex 10
va rog sa ma ajutati

Answer 1

0,8=8/10=4/5
0,6=6/10=3/5
0,4=4/10=2/5
4x/5=3y/5=2z/5      4x=3y=2z     y=4x/3    z=4x/2=2x

a)x+y+z=260
x+4x/3+2x=260
3x+4x+6x=780
13x=780
x=60
y=4*60/3=80
z=2*60=120


b)2x+3y+4z=245
2x+3*4x/3+4*2x=245
2x+4x+8x=245
14x=245
x=17,5
y=4*17,5/3=23,(3)
z=2*17,5=35

c)x²+y²+z²=1525
x²+(4x/3)²+(2x)²=1525
x²+16x²/9+4x²=1525
9x²+16x²+36x²=13725
61x²=13725
x²=225
x=√225=15
y=4*15/3=20
z=2*15=30

d)1/x+1/y+1/z=0,25
1/x+1/(4x/3)+1/2x=25/100
1/x+3/4x+1/2x=1/4
(4+3+2)/4x=1/4
9/4x=1/4
9/x=1
x=9
y=4*9/3=12
z=2*9=18