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於Quadratic function
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1. x 30 40 55 70 75 80 y 219 249 238 163 127 87 2. x 35 40 55 65 ... 示更多 1. x 30 40 55 70 75 80 y 219 249 238 163 127 87 2. x 35 40 55 65 70 75 y 294 308 294 239 201 156 3. x 30 40 55 70 75 80 y 327 37 355 243 189 129 以上三Function是甚? 以y=a(x-h)^2+k表示.大家的回答. ^^
最佳解答:
Your provided data do not exactly match quadratic equations. A relative easy way is to approximate the quadratic equations by plotting the data on a graph. (1) http://img215.imageshack.us/img215/2840/graph1g.png 片考：http://img215.imageshack.us/img215/2840/graph1g.png The graph indicate a maximum of about 250.5 at x = 45. At x = 80, y is about 87 My estimation is y = a(x 45)^2 + 250.5 Sub (80,87) into equation yields a = -0.133 Therefore y = -0.133(x 45)^2 + 250.5 The result obtained by Excel quadratic curve fitting is y = 0.1352(x 44.96)^2 + 250.6 (2) http://img245.imageshack.us/img245/7848/graph2c.png 片考：http://img245.imageshack.us/img245/7848/graph2c.png The graph indicate a maximum of about 311 at x = 44.5. At x = 75, y is about 154 My estimation is y = a(x 44.5)^2 + 311 Sub (75,154) into equation yields a = -0.169 Therefore y = -0.169(x 44.5)^2 + 311 The result obtained by Excel quadratic curve fitting is y = 0.1699(x 44.67)^2 + 310.7 (3) http://img187.imageshack.us/img187/3365/graph3.png 片考：http://img187.imageshack.us/img187/3365/graph3.png The graph indicate a maximum of about 374 at x = 45. At x = 80, y is about 126 My estimation is y = a(x 45)^2 + 374 Sub (80,126) into equation yields a = -0.202 Therefore y = -0.202(x 45)^2 + 374 The result obtained by Excel quadratic curve fitting is y = 0.2015(x 44.94)^2 + 373.4
其他解答:
1 y=a(x-h)^2+k 2 y=a(x-h)^2+k 3 y=a(x-h)^2+k13413D6BADCE0D57
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