Question

I dont know how to do this
the answer isnt 4
pls answer if u know with simple working

Answer 1

13 matches

Explanation:

Notice 1st have 4 matches
then 2nd have 7 matches (since one is shared), this is 8-1

then 3rd have 10 matches (since two are shared) this is 12-2
Notice the pattern 4 matches per square minus one per aditional square from the first.
This give an equation
4n-1(n-1)= 3n+1
lets check
For n=1 matches= 3(1)+1=4

For n=2 matches= 3(2)+1=7

For n=3 matches= 3(3)+1=10
It works.
so

For n=4 matches= 3(4)+1=13