Tell last two quesions(pic is clear :)

7. If the coefficient of r^th,(r+1)^th and (r+12^th terms in the binomial expansion of (1+y)^m are in AP, then m and r satisfy the equation:


(1) m²-m(4r-1)+4r^​2+2=0           (2) m²-m(4r+1)+4r^​2-2=0
(3)  m ² -m (4r+1)+4r^​2 +2=0         (4)  m ² -m (4r-1)+4r^​2 -2=0

8. The Value of $C_4^{50}+\sum _{r=1}^6 C_3^{56-1}$ is 


$\left(1\right) C_4^{56} \left(2\right) C_3^{56} \left(3\right) C_3^{55} \left(4\right) C_4^{55}$