Question

Va rog dau 100 de puncte pentru exercitiile 7 si 8

Answer 1

7)
a)  -2/7 *a³ *b
b)  +3x
c) 4a²-9b²
d) x² +10x +25
e) (2xy - xy+y² +2x²-xy-x²-y²) :xy =x²:xy= x/y
f) (x-2)(x+2) /x(x+3) * (x+3)/(x+2) = x-2/x
g) [(2a-b)(a-b) + (3a-b)(a+b)] : [(a-b)(a+b)] * (a-b)/5a-b=
=[2a²-2ab-ab+b²+3a²+3ab-ab-b²]/(a+b) * 1/5a-b=
=(5a²-ab)/(a-b) * 1/5a-b=
=a(5a-b)/(a-b) *1/5a-b=
=a/a-b

8) a)
E(x) = [2(x+3) - 3 +4(x-3)] : (x-3)(x+3) * 4(x-3)/2x-3
E(x)= (2x+6-3+4x-12) : (x-3)(x+3) *4(x-3)/2x-3
E(x)= (6x-9)/ (x+3) * 4/2x-3
E(x)= 3(2x-3)/(x+3) * 4/2x-3
E(x)=3/(x+3) * 4/1
E(X)=12/x+3

b) expresia nu are sens daca numitorii sunt egali cu zero
 (x-3)(x+3)=0⇒ x=3 sau x=-3
2x-3=0⇒ 2x=3⇒x=3/2
pentru x∈{-2;2;3/2} expresia nu are sens

c) E(x) ∈ N⇒ 12/x+3 ∈ N⇒ x+3∈D12⇒ x+3∈ {1,2,3,4,6,12}
x∈{0,1,3,9}

Answer 2

7.a. Dupa simplificari: -2/7*a^3*b
b. 3x
c. 4a^2-9b^2
d. x^2+10x+25
e. 2-(x^2-xy+2xy-y^2-x^2-y^2)/xy= 2-(xy-2y^2)/xy=xy+2y^2
f. (x-2)/x