In the xy-plane, at what two points does the graph

[CurtisVincentBorns]

In the xy-plane, at what two points does the graph of y=(x+a)(x+b) intersect the x-axis?

(1) a+b=-1
(2) The graph intersects the y-axis at (0,-6)

The answer is C

I am totally just drawing a blank on how to solve this problem
I tried to factor the equation and got x^2+ax+bx+ab
It is a quadratic and will be graphed like U

I am not sure the relevance of statement 1

If I write the equation in y=mx+b form then statement 2 gives me b but I am not even sure if I can do that since its a quadratic equation and not a linear.

I'm confused

[tim]

this is definitely a quadratic rather than a linear equation. the thing is, you don't need to expand the quadratic because the factored form is more relevant to this problem. to find the points where the graph crosses the x-axis, plug in 0 for y, now (x+a)(x+b) = 0 so you know that x = -a or -b. in other words, the question is asking what the values of a and b are.

(1) tells us what the sum of a and b is, but we don't know them separately

(2) tells us what the product of a and b is, because if x=0, then y=ab

together we have enough information to solve for what we need. note that we will get two solutions, but since they just swap a and b we still know what the two numbers are..