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Ask a few math problems in senior two.
1. From the topic: Because triangle ABC has two solutions, CSIN 45' < B < C.

So 2 < c < 2 √ 2

Because the third side is greater than the difference between the two sides is less than the sum of the two sides.

0 < x: 2a+ 1, which means a >;; 2

a^2+(2a- 1)^2>; (2a+ 1)^2

Get a> eight

3. The four roots of the equations X 2-X+A = 0 and X 2-X+B = 0 (A is not equal to B) are

x 1 x2 x3 x4

x 1+x2= 1

x3+x4= 1

Four roots form a arithmetic progression, and the first term is 1/4.

Suppose x 1= 1/4.

The arrangement of the four roots is as follows

x 1 x3 x4 x2

x2=3/4

x3=5/ 12

x4=7/ 12

a=x 1*x2=3/ 16

b=x3*x4=

A+b= just solve it yourself.

4. Consider the monotonicity of the sequence: when n

5.A 1 * A2 * A3 = 9, and A 1 * A2 = 4, so a3=9/4.

A 1A2A3A4A5 = 25, A 1A3A4 = 16, so a5=25/ 16.

So a3+a5 = 6116.

6.an=sn-s(n- 1)=3^n- 1-(3^(n- 1)- 1)=3^n-3^(n- 1)