im unsure with these 2 questions

First one

The 4th term in the expansion  of     [ (2x^2y^3)  +  y ]^7   is given by

C(7, 3) * (2x^2y^3)^(7 - 3) * ( y)^3  =

C(7,3) * ( 2x^2y^3)^4 * y^3   =

35 * 2^4  *  (x^2 y^3)^4 * y^3  =

35 * 16  *  x^8 * y^12 * y^3  =

560 x⁸ y¹⁵

Here's the complete expansion :

128 x^14 y^21 + 448 x^12 y^19 + 672 x^10 y^17 + 560 x^8 y^15 + 280 x^6 y^13 + 84 x^4 y^11 + 14 x^2 y^9 + y^7

im actully thinking the second question is actually C , r=0.8 . the series dverges