I need help with algebra evaluate find (f-g)(3) given f(×)=×-2 and g(×)=-3x^2+16×-1

Question

Please help me understand this

Answer 1

Alright, Yanet, (f-g)(x) means we are going to subtract the two functions. (f-g)(3) means we are then going to plug in 3 for each x and solve. We can also do it reversed. I'll do it both ways.

 

(f-g)(x) = x - 2 - (-3x² + 16x - 1) 

                x - 2 + 3x² - 16x + 1

                3x² - 15x - 1

(f-g)(3) = 3(3²) - 15(3) - 1

                 3(9) - 45 - 1

                 27 - 45 - 1

                 -19

 

Or...

 

 

f(3) = 3 - 2 = 1

g(3) = -3(3²) + 16(3) - 1 

           -3(9) + 48 - 1

           -27 + 48 - 1

           20

 

(f-g)(3) = 1 - 20 = -19

 

Hope this helps!