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Find the analytic expression of quadratic function It is known that two points a (12,82) B (14,81) B are the vertices of the function, and the solution set with F (x) greater than 80 is obtained Wrong! Point a is the vertex.
F(x)=a(x-12)^2+82
Bring in (14,81)
a=-1/4
F(x)=-1/4x^2+6x+46
-1/4（x-12）^2+82>80
(x-12)^2
Get quadratic function expression according to image
Given the image of quadratic function, its expression can be obtained by (- 6,0) (0,4) (2,0)
Let the quadratic function y = AX2 + BX + C0 = 36a-6b + c.14 = C.20 = 4A + 2B + c.32 bring in 1,3 to get 18a-3b + 2 = 0.42a + B + 2 = 0.55x3 + 4 to get 24a + 8 = 0, a = - 1 / 3, B = - 4 / 3, C = 4
How to calculate the quadrilateral area in the image of quadratic function in junior high school mathematics?
About the maximum area!
Divide it into two triangles, calculate the area respectively and add them
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