if f(x)=4x^2-x+1, then f(a+1) equals

Question

Answers:

 

1. 4a^2-a+6

 

2. 4a^2-a+4

 

3. 4a^2+7a+6

 

4. 4a^2+7a+4

Answer 1

Substitute (a + 1) for x.  Then simplify

 

 

f(a + 1) = 4(a + 1)² - (a + 1) + 1

        

            = 4(a² + 2a + 1) - a - 1 + 1

 

            = 4a² + 8a + 4 - a - 1 + 1

 

            = 4a² + 7a + 4