Cina ma poate ajuta cu un exercitiu ?Va rog ! a) daca x/3=y/4 si 3x +4y =75 , determinati numerele x si y b) daca x/5=y/7 si x+y =24, determinati numerele x si y c)daca x/4 = y/5 = z/6 si x + y + z = 15 , determinati numerele x, y si z d) daca x/2 =y/3 =z/5 si 2x +3y + 5z =76, determinati numerele x, y si z

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Răspunsuri

2014-08-10T13:36:57+03:00
A)x/3=y/4=k

x=3k
y=4k

3x+4y=75

3*3k+4*4k=75
9k+16k=75
25k=75
k=3

x=3*3=9
y=3*4=12

b)x/5= y/7=k
x=5k
y=7k

x+y=24
7k+5k=24
12k=24
k=2

x=5*2=10
y=7*2=14

c)x/4=y/5= z/6=k
x=4k
y=5k
z=6k

x+y+z=15
4k+5k+6k=15
15k=15
k=1

x=4
y=5
z=6

4)x/2= y/3= z/5=k
x=2k
y=3k
z=5k

2x+3y+5z=76
2*2k+3*3k+5*5k=76
4k+9k+25k=76
38k=76
k=2

x=2*2=4
y=3*2=6
z=5*2=10
25 4 25
2014-08-10T13:39:51+03:00
A. x/3=y/4⇒4x=3y⇒4x-3y=0 inmultim cu 4⇒16x-12y=0
inmultim relatia data cu 3⇒9x+12y=225
adunam cele doua relatii obtinute
25x=225, x=9, y=4x/3=12
b. x/5=y/7
x/y=5/7
(x+y)/y=12/7
24/y=12/7
y=24*7/12=14, x=5y/7=10
c. x/4=y/5=z/6=k⇒x=4k, y=5k, z=6k
4k+5k+6k=15, 15k=15, k=1
x=4, y=5, z=6
d. x/2=y/3=z/5=k⇒x=2k, y=3k, z=5k
4k+9k+25k=76
38k=76, k=2
x=4, y=6, z=10
11 4 11