Hi! Just wanted to say your site is really helpful. I am trying to figure out some quadratics and I think I've got it, but this one question I have just isn't working. Here it is:
6x+8=-x2
and so far I have:
6x+8=-x2
x2+6x+8=0
=(x+4)(x+2
right?
But heres the problem... when I check my answer it says my points should be (-2,-4). So what am I doing wrong? I have check the book soo many times to see if I am copying the question right and I am. Also, I was wondering how you know which point comes first? Thanks!
Hi Jess,
Right. So far, you factored the polynomial x2+6x+8 as the product (x+4)(x+2).
If the question is to solve the equation x2+6x+8 = 0, that is, find the values of x for which the equation x2+6x+8 = 0 is true, then your factorization is useful, because it reduces the question to solving the equation
(x+4)(x+2) = 0,
and A PRODUCT IS ZERO IF AND ONLY IF ONE OF THE FACTORS IS ZERO. Hence you only need to solve x+4 = 0, and you find x = -4, and x + 2 = 0, and you find x = -2; hence the two answers are x = -2 and x=-4, and this is what the answer key says.
Claude