a)f(-2) = 7
f(1) = -2
-2a + b = 7
a + b = -2
a = -2 -b = -(b + 2)
2(b + 2) + b = 7
2b + 4 + b = 7
3b = 3
b = 1
a = -(1 + 2) = -3
f(x) = -3x + 1
b)
[tex]f(a+b)\leq f(a) + f(b)\\a(a+b) \leq a^2 + b + ab + b\\a^2 + ab \leq a^2 + 2b + ab\\0 \leq 2b\\2b \geq 0\\b \geq 0\\b\in [0,+\infty)[/tex]
c)
[tex]g(-1)=-3\cdot(-1) + 1 = 6 + 1 = 7\\g(2) = -3\cdot 2 + 1 = -6+1 = -5\\Im\:g = [-5,7][/tex]
Valorile functiei [tex]g[/tex] sunt din intervalul [-5,7]
