Select the appropriate values of x that are solutions to f(x)=0, where f(x)=-6x^2 +8x+3

Question

A: {1.64,-0.31}

B: {-6,8}

C: {-1.33,-0.50}

D: {-2.00,2.67}

Answer 1

Hello, Kristen.

 

What you need to do is use the quadratic formula 0=-6x^2+ 8x+ 3

 a=-6

b= 8

c= 3

 

Let me start by doing the determinant, what's inside the sq. root sign.

 

b^2-4ac= 8^2-4(-6)(3)                Evaluate the exponent 

                  64-4(-6)(3)                Multiply (-4)(-6)(3)

                  64 + 72

                        136

Following the quadratic formula, we have two answers

( note the square root of 136 is approximately 11.66)

 

a) [-b + sq. rt. of 136]/2a

    [-(8)+(11.66)]/2(-6)= (3.66)/(-12)= -.31

 

b) [-b - sq. rt. of 136]/2a

    [-(8) -(11.66)]/2(-6)= (-19.66)/(-12)= 1.64

 

 I rounded both answers to the hundredths place value.  So, the answer must be a. 

 

Good luck and thanks for posting.

D.Y. Taylor

                        

 

 

     

      

              

            

 

      

               

                

 

 

     

       

                        

      

Answer 2

Do this one the same way I did the previous problem from you.