Question

What constant would be added to the expression x2−7xx2−7x in order to make it a perfect square?

Answer 1

ok

assuming ya mean $x^2-7x$
since the quadratic coefient is 1, take 1/2 of the liner coeficient and square it
the linear coefient is -7
half of that is -7/2
squared we get 49/4
add that to get
$x^2-7x+\frac{49}{4}$
it factors to
$(x-\frac{7}{2})(x-\frac{7}{2})$ or $(x-\frac{7}{2})^2$

you must add $\frac{49}{4}$ to make it a perfect square