1.
(1)(m+n)/2=b/2(就是对称轴)=2
∴b=2, m+n=4,m/n=1/3,可以解出,m=1,n=3
(1,0)代入,得y=-x^2+4x-3
(2)由题意得P(0,-3),
y=0,算出x=0或x=4
S△ACP=3*4/2=6
2.
x1-y1=2,x2-y2=2
所以x1-y1+x2-y2=x1+x2-(y1+y2)=4
x1+x2=4k,y1+y2=-k^2
算出 k=-2
1.
(1)(m+n)/2=b/2(就是对称轴)=2
∴b=2, m+n=4,m/n=1/3,可以解出,m=1,n=3
(1,0)代入,得y=-x^2+4x-3
(2)由题意得P(0,-3),
y=0,算出x=0或x=4
S△ACP=3*4/2=6
2.
x1-y1=2,x2-y2=2
所以x1-y1+x2-y2=x1+x2-(y1+y2)=4
x1+x2=4k,y1+y2=-k^2
算出 k=-2