What is the relative maximum and minimum of the function?

f(x) = 2x^2 + 28x - 8
A. Minimum Value: -106 Range y -7
B. Minimum Value: -106 Range y -106
C. Minimum Value: 7
Range y 7
D. Minimum Value: -7 Range y -7

Question

What is the relative maximum and minimum of the function?

f(x) = 2x^2 + 28x - 8
  A. Minimum Value: -106 Range y > -7 	
  B. Minimum Value: -106 Range y > -106 	
  C. Minimum Value: 7 
Range y > 7 	
  D. Minimum Value: -7 Range y > -7

campbell_st · Answer

well since its a concave up parabola its going to have a minimum. 

do you know calculus...?

anonymous · Answer

Nope lol

anonymous · Answer

It only has  minimum.

campbell_st · Answer

ok... well use the line of symmetry... to help find the vertex... this is where the minimum will occur

the general form for the line of symmetry is 

$$x = \frac{-b}{2 \times a}$$

in your question you have b = 28 and a = 2

can you calculate the value for the line of symmetry?

anonymous · Answer

x= -28/ 2*2? i can put that into a calculator and what i get will be my answer right?

campbell_st · Answer

thats right...but make sure the denominator is (2 x 2)   in brackets

anonymous · Answer

okay :) Let me plug it in

anonymous · Answer

I got -7 ...but idk what the other number is ..

anonymous · Answer

Its either A or D

campbell_st · Answer

great... so plug x = -7 into your equation and that will give the minimum value of the curve.

anonymous · Answer

Oh okay lol

campbell_st · Answer

you need to take care with the substitution as 

2*(-7)^2   is a positive number...

anonymous · Answer

98?

campbell_st · Answer

thats great so its then 

$$98 + 28 \times (-7) - 8$$

to get the minimum value

anonymous · Answer

Its says math processing error ..

anonymous · Answer

Im thinking its A though :) So thanks for taking me step by step :)

anonymous · Answer

It's D @SkiTTleoooo47