To find the largest real number c such that 1 is in the range of f(x)=x2−5x+c−3x+8, we first simplify the function to: f(x)=x2−8x+(c+8) For 1 to be in the range of f(x), there must be some value(s) of x for which f(x)=1. This can be written as: x2−8x+(c+7)=0 For this equation to have at least one real root, the discriminant of the quadratic equation must be non-negative: Δ=b2−4ac Δ=(−8)2−4∗1∗(c+7) Δ=64−4c−28 Δ=36−4c For Δ to be non-negative, 36−4c≥0, or c≤9. Therefore, the largest real number c for which 1 is in the range of f(x) is c = 9.