solve the system of equations (10a+3b+4c+d+e=0,11b+2c+2d+3e+f=0,15c+4d+5e+4f+g=0,2a+b-3c+12d-3e+f+g=0,6a-5b+3c-d+17e+f=0,3a+2b-3c+4d+e-16f+2g=0,4a-6b+c+d+3e+19g=0)

 Calculus problem S(n)=1^2+3^2+5^2+...+(2n-1)^2 ?

Evaluate the limit without using hopital rule or taylor series.

A square has 36 sub-squares in it. How to Number each sub squares from 1 to 36, to make the sum of vertical, the sum of horizontal, and the sum of cross line are the same .Describe in general if possible.

Find the value: P=sin(1⁰)sin(3⁰)sin(5⁰)...sin(89⁰) ?