Question

帮下忙,初4二次函数抛物线y=1/2x^2-3/2mx-2m 交X轴A(X1,0)B(X2,0)交Y轴于点C且x1

Answer 1

点C（0,-2m）；OC=|2m|;

交于三点,则可知-2m0;

则OC=2m;

OA+OB=x2-x1,

则(OA+OB)^2=(x2-x1)^2= (x2+x1)^2 -4·x1·x2 = （3m）^2 +16m

=24m+1;

→9m^2 +8m -1 =0;

m=1/9;

则解析式为

y=1/2x^2-1/6x-2/9