Question

plz guys solve these all questions with explanation......​

Answer 1

Answer:

Step-by-step explanation:

Q.no-4

n(n-3)/2=9

n(n-3)=18

n^2-3n=18

n^2-3n-18=0

n^2-6n+3n-18=0

n(n-6)+3(n-6)=0

n=6 n= -3

N=6(ans)