Question

Va rog frumos c,d si a,b,c

Answer 1

c)

(6x+4y)/(5x+2y)=3/2

⇒2×(6x+4y)=3×(5x+2y)

⇒ 12x+8y=15x+6y

⇒ 8y-6y=15x-12x

⇒ 2y=3x

⇒x/y=2/3

d)

(5x-4y)/(2x-y)=7/3

⇒ 3×(5x-4y)=7×(2x-y)

⇒ 15x-12y=14x-7y

⇒15x-14x=12y-7y

⇒x=5y

⇒x/y=5

a)

x/3=y/4=k; x=3k si y=4k

dar 3x + 4y = 75

9k + 16k = 75

25k =75k = 3

deci x=3k si y=4k

x = 9 si y = 12

b)

x/5=y/7 =k

x=5k ; y=7k

x+y=24

7k+5k=24⇒12k=24⇒k=24:12=2

k=2

x=5k=5×2=10

y=7k=7×2=14

x = 10 si y = 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 = 4k = 4

y = 5k = 5

z = 6 = 6k = 6

x = 4; y = 5 ; z = 6