f(0)=1
f(x)=a×0+b×0+c=c=1
f(x+1)-f(x)
= [ a(x+1)²+b(x+1)+1] - [ ax²+bx+1]
= ax² + 2ax + a² + bx + b + 1 - ax² - bx - 1
=(2a+b-b)x + a²+b
= 2ax + a² + b = 2x
∴2a=2 a=1
b= -1
∴f(x)=x²-x+1
f(0)=1
f(x)=a×0+b×0+c=c=1
f(x+1)-f(x)
= [ a(x+1)²+b(x+1)+1] - [ ax²+bx+1]
= ax² + 2ax + a² + bx + b + 1 - ax² - bx - 1
=(2a+b-b)x + a²+b
= 2ax + a² + b = 2x
∴2a=2 a=1
b= -1
∴f(x)=x²-x+1