Demostrar la siguiente identidad: cos2α= cos²α - sen²α

F(x)=x/2-2 and g(x)=2x^2+x-3 find (f+g)(x)

Bring the fraction a/a-4 to a denominator of 16-a^2

You are choosing between two health clubs. club a offers membership for a fee of $ 28 plus a monthly fee of $ 20. club b offers membership for a fee of $ 20 plus a monthly fee of $ 22. after how many months will the total cost of each health club be the same? what will be the total cost for each club? in __ months the total cost of each health club will be the same.