m？ +2m-3=0, so: m 1=-3, m2= 1.

Because the original equation is a quadratic equation, m= 1 is unreasonable, so it is discarded.

2) Solution: Because 2 * 2 = 4 < 5 < 3 * 3 = 9,

So 2 0,

Because x 1+x2=-p, x1x2 = q.

Therefore, -p < 0 and q > 0.

So p > 0 and q > 0.

So choose a.

6) solution: according to the meaning of the question, x 1+x2=- =a2-2a- 15,

Because x 1+x2=0,

So a2-2a- 15=0,

So a=5 or a=-3,

Because when a=5, x2+4=0 has no real root,

Therefore, the value of a is -3.

7) solution: according to the meaning of the question, M 2+Mn+M = 0.

Namely: m(m+n+ 1)=0, m≠0.

So the value of m+n is-1.

8) solution: according to the meaning of the question

X2-9x+20=0，

(x-4)(x-5)=0，

Therefore, x 1=4, x2 = 5；;

While that length of the base of the isosceles triangle is 8,

When x=4, 4, 4 and 8 cannot form a triangle.

So waist length x=5,

Let the height be h, which is obtained by Pythagorean theorem:

h=3，

So the height is 3,

Therefore, the area of the triangle is 0.5 ×8×3= 12.

9) Solution: The original formula = x 2-6x+9 = (x 3) 2 = 0.

D: X=3

10) solution: Assuming that the price of each shirt is reduced by X yuan, the shopping mall can earn 2 100 yuan every day.

(45-x)(20+4x)=2 100，

The answer is x 1= 10, X2 = 30.

X = 30 is because the inventory is reduced as soon as possible.

Every shirt has to be reduced in price, 30 yuan.

Finally, I wish you success in your studies, don't rely too much on others, and learn methods. Good luck! And remind those who want to steal others' achievements by copying and pasting, go away. I also hope that the questioner's eyes are discerning.