Question 105953
There is a special product formula in algebra such that:
{{{(a - b)^2 = a^2 - 2ab + b^2)}}}
Applying this to the expression {{{(49x^2 - 42x + 9)}}}:
{{{a = sqrt(49) = 7}}}
{{{b = sqrt(9) = 3}}}
check:
{{{2ab = 2 * 7 * 3 = 42}}}
so:
{{{49x^2 - 42x + 9 = (7x - 3)^2}}}