Question

Utilizand proportiile derivate,determinati numarul rational x din proportiile:

a)x/x+5=4/9:
b)x/x+11=-3/11;
c)4+x/x=9/2;
d)x/5=-x+6/-7;
e|)8/x=15/23+x;
f)x+7/4x=1/1,2;
g)14-x/x=60-2x/14+2x;
h)2x/7+2x=4x+1/4x+2,5;
i)bara deasupra lui x4/4x=4/7;
Va rog frumos!

Answer 1

a)x/(x+5)=4/9
4x+20=9x
5x=20
x=4

b)x/(x+11)=-3/11
-3x-33=11x
14x=-33
x=-33/14

c)(4+x)/x=9/2
8+2x=9x
7x=8
x=8/7

d)x/5=(-x+6)/(-7)
-5x+30=-7x
2x=-30
x=-15

e|)8/x=15/(23+x)
15x=184+8x
7x=184
x=184/7

f)(x+7)/4x=1/1,2
(x+7)/4x=5/6
6x+42=20x
14x=42
7x=21
x=3

g)(14-x)/x=(60-2x)/(14+2x)
(14-x)/x=(30-x)/(7+x)
30x-x²=98-7x+14x-x²
30x=98+7x
23x=98
x=98/23


h)2x/(7+2x)=(4x+1)/(4x+2,5)
8x²+5x=28x+8x²+7+2x
5x=30x+7
25x=-7
x=-7/25
   __ __
 i)x4/4x=4/7
(10x+4)/(40+x)=4/7
160+4x=70x+28
66x=132
x=132/66
x=2