Product of numbers Pair of numbers whose product is $+7$ and whose sum is $-8$. 
Factorise $x^{2} - 8x + 7$.
I can factorise but it's just I can't find any products of $+7$ and that is a sum of 
$-8$. Any idea? Thanks guys!
Thanks.


your questions answer are already users have given so i'm not repeating them.
  sometimes factorization is not easy because number are too big to manually calculate or may be fractional so try this formula as alternative.
  roots for equation $(ax^2+bx-c)=0$ is,
  $x=\dfrac{-b+\sqrt{b^2-4\cdot a\cdot c}}{2\cdot a}$ , 
  $\dfrac{-b-\sqrt{b^2-4\cdot a\cdot c}}{2\cdot a}$ 

