(-1)(-1).... upto 39 terms ? (+1)(+1)(1) upto ....43 terms ? (-2)(-2)

Dear student,

(-1)(-1)(-1)..... up to 39 terms = -1
As there are odd number of negative signs ,the product will be a negative sign
As ${(-1)}^n$   = (-1) if n is an odd number
${(-1)}^n$ = 1 if n is an even number

(+1)(+1)(1) upto ....43 terms = 1 
As the sign remains the same 
"+" * "+" = "+"

(-2)(-2) = 4
As "-" * "-" = "+"
Product of negative signs gives positive sign.

Regards