Question 104668
{{{x^2 + 8x + 7}}}

I want you to know the shortcut of this method. So, please access my lesson "Factoring trinomials: SHORTCUT!!!" then go back to this page.


Using the quadratic formula,


___________________{{{x=(-8+-sqrt(8^2-4*1*7))/(2*1)}}}__________________________
___________________{{{x=(-8+-sqrt(64-28))/(2)}}}________________________________
___________________{{{x=(-8+-sqrt(36))/(2)}}}_)_________________________________
___________________{{{x=(-8+- 6)/(2)}}}_________________________________________
_______________{{{x=-4+3}}} or {{{x=-4-3}}}_____________________________________
_________________{{{x=-1}}} or {{{x=-7}}}_______________________________________

If x=-1,x+1=0.
If x=-7,x+7=0.

Thus, these are the factors so,
{{{x^2 + 8x + 7=(x+1)*(x+7)}}}

Check:
{{{(x+1)*(x+7)=(x*(x+7))+(1*(x+7))}}}
___________={{{(x^2+7x)+(x+7)}}}
___________={{{x^2+(7x+x)+7}}}
___________={{{x^2 +8x +7}}}

Thus, my lesson is correct and and the resulting answer are also correct!


Power up,
HyperBrain!