(1) According to the symmetry axis formula, the value of m can be found as 1/6. Analytical method: the formula is -b/2a = 4, where a is the coefficient m of x2 and b is the coefficient of x -(2m+ 1).

(2) The analytical formula of 2)BD is Y=7/6X-7. Analytical method: When y=0, x is equal to 2,6, A (2 2,0) and B (6 6,0) respectively. Let the straight BD equation y=kx+b, so k=-b/6. Point D from the meaning of the question and the linear equation is

I hope I did the right thing. I haven't done it for a long time. Senior three is boring.