In a geometric series, find a1 if Sn = 16,200, r = 2, and n = 4. PLS HELP ASAP

Find the slope and the y-intercept if there's one and the equation of the line given these two points( 3, 2) and( 3, -4)

Sketch the vector field vector f( vector r ) = 8vector r in the xy-plane. select all that apply. the length of each vector is 8. the lengths of the vectors decrease as you move away from the origin. all the vectors point away from the origin. all the vectors point in the same direction. all the vectors point towards the origin. the lengths of the vectors increase as you move away from the origin.

Which is the best estimate of the product of 0.9 x 0.88? 0 0.25 0.5 1