Question

Va rog imi trebe maine la scoala . 2 si 3 .

Answer 1

2)

2/(x+1)

D₂ = { 1, -1, 2,-2}

x+1=1⇒x=0∈ Z

x+1=-1⇒x=-2∈ Z

x+1=2⇒x=1∈ Z

x+1=-2⇒x=-3∈ Z

x∈{0, -3, -2, 1}

(x-1)/(3x+2)   inmulim cu 3 numaratorul

(3x-3)/(3x+2)

(3x+2-5)/(3x+2)∈Z

(3x+2)/(3x+2)-5/(3x+2) ∈Z

1-5/(3x+2) ∈Z

5/(3x+2) ∈Z

D₅={-5;-1;1;5}

3x+2=-5 ⇒ 3x= -7, x=-7/3∉Z

3x+2=-1⇒x=-3/3=-1∉Z

3x+2=1⇒x=-1/3∉Z

3x+2=5⇒x=3/3=1

x∈{-7/3;-4/3;-2/3;1}  dar doar 1 ∈Z

3.

a/3=b/5/c/11=k

a=3k,  b=5k, c=11k

3a+b-c=12

9k+5k-11k=12

3k=12⇒k=4

a=3k=3×4=12

b=5×4=20

c=11×4=44

Answer 2

(x-1)/(3x+2)∈Z

(3x-3)/(3x+2)∈Z

(3x+2-5)/(3x+2)∈Z

(3x+2)/(3x+2)-5/(3x+2) ∈Z

1-5/(3x+2) ∈Z

5/(3x+2) ∈Z

3x+2∈{-5;-1;1;5}

3x∈{-7;-4;-2;3}

x∈{-7/3;-4/3;-2/3;1}∩Z={1}

a doua e mult m,ai simpla cu ea ar trebui inceput

x+1∈{-2;-1;1;2}

x∈{-3;-2;0;1}∩Z={-3;-2;0;1}

pe 3 ti-l incep

a/3=b/5=c/11=k

a=3k

b=5k

c=11k

3a+b-c=9k+5k-11k=3k

3k=12

k=4

a=3*4=12

b=5k=...

c=11k=...