(x+2)(x-m)& lt; 0
When m & gt-2, x+2 >; 0,x & gt-2,-2 & lt; x & ltm
When m & lt-2, x+2
When m=2 and (x-2)2≥0, there is no solution.
The second question assumes that the common ratio is n, then
a 1( 1+n^2)=5,a 1n^3( 1+n^2)=40
When the two formulas are divided, n 3 = 8 and n = 2 are obtained.
a 1( 1+2^2)=5,a 1=5
A4=A 1Xn^3= 1X8=8
S5 = 1+2+4+8+ 16 = 3 1