cho f(x) = ax^2 + bx+c. a) tính f(1),f(3).b) biết 5a -b +2c=0. chứng minh f(1),f(2) bé hơn hoặc bằng 0. c) a=1, b=2,c=3.chứng minh f(x) không có nghiệm

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The last answer choice

Idon't see any graph, however the graph of the function : f(x) = x²-2x+3 is a parabola: 1) open upward (since a> 0)2) it intersects y-axis in 3 (y=3)3) its axis of symmetry is x = +1 ( -b/2a)4) it's minimum is y = -2, so its vertex is (1,-2)5) it doesn't intersect the x-axis since discriminant < 0