11)
a)A(a,a²) € G f
f(x)=2x+3
f(a)=a²
2a+3=a²
-a²+2a+3 = 0
∆ (delta) = b²-4ac
a= -1
b=2
c=3
∆ = 2² - 4•(-1)•3 = 4+12 = 16
a 1 , a 2 = -b+-√∆ supra 2 a
a 1 = -2 + 4 supra -2 = 2 supra -2 => a 1 = -1
a 2 = -2-4 supra -2 = -6 supra -2 => a 2 = 3
12)
a) A(1;3) € G f
B(2;5) € G f
f(x)=ax+b
f(1) = 3
a+b=3
a = -b+3
B(2;5)
f(2) = 5
2a+5=5
