a, $(x-3^2)=1$
$x=1+3^2$
$x=1+9$
$x=10$
Vậy $x=10$
b, Sửa đề: $-4(5+35x)^2=-36$
$(5+35x)^2=-36:-4$
$(5+35x)^2=9$
$TH1: 5+35x=3$
$35x=3-5$
$35x=-2$
$x=-2:35$
$x=\dfrac{-2}{35}$
$TH2: 5+35x=-3$
$35x=-3-5$
$35x=-8$
$x=-8:35$
$x=\dfrac{-8}{35}$
Vậy `x∈{\frac{-2}{35}, \frac{-8}{35}}`
