Question

How do you do this algebra question

Answer 1

$C. Look:\\ Let's\ substitute\ 1.2.3\ or\ 4\ for\ n:\\ stage\ 1:\frac{n}{2}(n+1)=\frac{1}{2}(1+1)=1=1 square\\ stage\ 4:\frac{4}{2}(4+1)=2*5=10=10\ squares\\ Count\ it\ in\ the\ picture\ and\ compare$