$a)$

$A=\left(3,-5\right)$

$f\left(3\right)\stackrel{?}{=}-5$

$f\left(3\right)=-4\cdot 3+7=-12+7=-5$

$B=\left(-0,25;6\right)$

$f\left(-0,25\right)\stackrel{?}{=}6$

$f\left(-0,25\right)=-4\cdot \left(-0,25\right)+7=1+7=8\ne 6$