Respuesta :

This is a parabola which looks like an inverted U. Its will have a maximum value  when t = 7  as we see from  the vertex form below:-

- t^2 + 14t - 40 
= - ( t - 7)^2 + 49 - 40
= -(t - 7)^2 + 9

There is an axis of symmetry at  x = 7.

so a is true  since 7 is the maximum value of the function and  its less at t = 6.
c is also true   because  of the symmetry about t = 7

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