说明：  混凝土的抗压强度随养护时间的延长而增加，现将一批混凝土作成12个试块，记录了养护日期x（日）及抗压强度y（kg/cm2）的数据：求型回归方程 示例方程在内
(The compressive strength of concrete with curing time and increase the extension, now make a number of concrete block 12, recording the date of the conservation of x (day) and compressive strength of y (kg/cm2) of data: the regression equation for sample-based equation, including)