Identify the two expressions that are perfect squares.
$k^4+4k^2+4$k4+4k2+4
$k^2-9k+81$k2−9k+81
$k^2+4$k2+4
$1^2-k+k^2$12−k+k2
$k^2+5k+\frac{25}{4}$k2+5k+254
Determine if each expression is a difference of two squares.
Determine if each expression is a difference of two squares.
Fully factorise: $5\left(a+b\right)+v\left(a+b\right)$5(a+b)+v(a+b)