.第三章课后习题第二题(1)做出x,y的散点图，确定所要的回归模型x1=0.1:0.01:0.18;x2=x1,0.2,0.21,0.23;y=42.0,41.5,45.0,45.5,45.5,47.5,49.0,55.0,50.0,55.5,55.5,60.5;plot(x2,y,*)（2） 做回归分析 x=ones(12,1),x2; b,bint,r,rint,stats=regress(y,x)运行结果结果表明：决定系数R2=0.9229接近1，F1-0.05（1，12-2）=0.0041119.7470P=0.00000.05故回归模型：y=26.8909+141.7415x成立.
