human
Prove statements involving multiples On what line is the first mistake when proving \( (n+1)^{2}-(n-1)^{2} \) is divisible by \( 4 \) ? \( n^{2}+2 n+1-\left(n^{2}-2 n+1\right) \quad \) Line \( 1 \) \( n^{2}+2 n+1-n^{2}-2 n+1 \quad \) Line \( 2 \) \[
2
\]

Line \( 3 \) Line \( 1 \)
gpt
Ignores negative sign when expanding bracket