Question

Preciso do calculo

seja f uma função real definida pela lei f(x) =ax-3. Se -2 é a raiz da função, qaual o valor de f(3)? ​

Answer 1

$\large\boxed{\begin{array}{l}\sf f(x)=ax-3\\\sf se~-2\,\acute e\,ra\acute iz\,ent\tilde ao\\\sf f(-2)=0.\\\sf f(-2)=a\cdot(-2)-3\\\sf f(-2)=-2a-3\\\sf -2a-3=0\\\sf 2a=-3\\\sf a=-\dfrac{3}{2}\\\\\sf f(x)=-\dfrac{3}{2}x-3\\\sf para~obter\,f(3)\,temos:\\\sf f(3)=-\dfrac{3}{2}\cdot3-3\\\\\sf f(3)=-\dfrac{9}{2}-3=\dfrac{-9-6}{2}=-\dfrac{15}{2}\end{array}}$