Question

Preciso da conta, não entendi nada

Answer 1

f(x)=5x²+ax+b

f(a)=5a²+a.a+b

b=5a²+a²+b

6a²+b=b

6a²=b-b

6a²=0

a²=0/6

a²=0

$a=\sqrt{0}=0$

f(b)=5b²+ab+b

a=5b²+ab+b

0=5b²+0.b+b

5b²+b=0

b(5b+1)=0

5b+1=0

5b=-1

$b= -\frac{1}{5}$

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$a+b=0+(-\frac{1}{5} )=0-\frac{1}{5}=-\frac{1}{5}$

alternativa b