Question

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Answer 1

Răspuns:

Explicație pas cu pas:

Answer 2

a)

$\it f(x)=\dfrac{5}{2}x-0,5\ \Rightarrow f(x)=\dfrac{5}{2}x-\dfrac{1}{2} \\ \\ \\ A(1,\ 2)\in Gf\ \Leftrightarrow f(1)=2\ \Leftrightarrow \dfrac{5}{2}-\dfrac{1}{2}=2\ \Leftrightarrow 2=2\ \ (A)\\ \\ \\ B(7,\ 17)\in Gf\ \Leftrightarrow f(7)=17\ \Leftrightarrow \dfrac{5}{2}\cdot7-\dfrac{1}{2}=\dfrac{35}{2}-\dfrac{1}{2}=\dfrac{34}{2}=17\ (A)$

b)

$\it Fie \ \ a\ \in\ \mathbb{N},\ \ 1\leq a\leq7\ astfel\ \hat\imath nc\hat at\ f(a)\in\mathbb{N}.\\ \\ f(a)=\dfrac{5}{2}a-\dfrac{1}{2}=\dfrac{5a-1}{2}\in\mathbb{N} \Rightarrow 5a-1=par \Rightarrow a=impar\\ \\ 1\leq a\leq7 \Rightarrow a\in\{1,\ 3,\ 5,\ 7\}$

f(1) = 2 ⇒ A(1,  2

f(7) = 17) ⇒ B(7,  17)

f(3) = 7 ⇒ C(3,  7)

f(5) = 12 ⇒ D(5,  12)