What operation is used in obtaining the succeding terms in an arithmetic sequence?​

Afamily has five members. a mom, a dad, two sisters, & a brother. the family lines up single file. what is the probabillity that the mom is at the front of the line

Find the area of the region that is inside r=3cos(theta) and outside r=2-cos(theta). sketch the curves.

Write the equation in general quadratic form: plz !