Question

Find the missing term in the following expressions to make each a perfect square.
$25x^2+40xy+\square$

Answer 1

$25x^2+40xy+\square$

$(5x{)}^2+2\times 5x\times 4y+\square$

$A^2+2\times A\times B+B^2$

$B\Rightarrow 4y$

$B^2=(4y{)}^2$

$=16y^2$

$(5x{)}^2+2\times 5x\times 4y+16y^2$

Hence, missing term$=16y^2$

This is the answer.