sama bantuin yg nomor 10 sama 11 plisss

turunan
f(x) = a tan x + bx
f '(x) = a sec² x + b

f' (π/4) = 3----> a sec² (π/4)  + b = 3 --> 2a + b = 3
f '(π/3) = 9 ---> a sec² (π/3)  + b = 9 --> 4 a+ b = 9
kurangkan (2a - 4 a)  = 3 - 9
-2a = - 6
a = 3
2a + b  =  3
2(3) + b = 3
b = - 3

a+b = 3 + (-3) = 0