Answer:
Correct option: C.
Step-by-step explanation:
(Assuming the correct function is R(x) = 2x^2 + 3x + 5)
To find the input value that gives the value of R(x) = 19, we just need to use this output value (R(x) = 19) in the equation and then find the value of x:
[tex]R(x) = 2x^2 + 3x + 5[/tex]
[tex]19 = 2x^2 + 3x + 5[/tex]
[tex]2x^2 + 3x -14 = 0[/tex]
Solving this quadratic function using the Bhaskara's formula (a = 2, b = 3 and c = -14), we have:
[tex]\Delta = b^2 - 4ac = 9 + 112 = 121[/tex]
[tex]x_1 = (-b + \sqrt{\Delta})/2a = (-3 + 11)/4 = 2[/tex]
[tex]x_2 = (-b - \sqrt{\Delta})/2a = (-3 - 11)/4 = -3.5[/tex]
So looking at the options, the input to the function is x = 2
Correct option: C.
