Question 996378
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You are given that the polynomial  y = {{{ax^2 + bx + c}}}  has the value  y=1  at  x=-1.


It means that  (substitute this value of  x=-1  into the polynomial) 


1 = y = {{{a*(-1)^2 + b*(-1) + c}}} = a*1 -b + c = a - b + c.


Again:   a - b + c = 1.


It is case  D).