earthsea98: find the zeros of this equation
y=x^2 + 6x + 5
Vertex= (-3,.4)
The vertex isn't important.
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I'll do a different one and then you can do your own one.
y=x
2+6x+8
This is a parabola, the roots are where the parabola crosses the x axis (the x intercepts if you like)
The equation of the x axis is y=0.
So what you are really doing here is finding where y=0 and y=x
2+6x+8 intersect.
You are solving these 2 equations simultaneously.
since we know that y=0 and y=x
2+6x+8 we can say that
x
2+6x+8 = 0 This is usually the starting point but you should know why!
To answer this you need to factorise it.
You need to find 2 numbers that add to 6 and multiply to 8
It is easiest to think about the multiply first.
They have to mult to a positive number therefore they must both be + or both be -
They have to add to a positive so they both must be positive.
1*8=8 but 1+8 is not 6 so that's no good
2*4=8 and 2+4=6 great the numbers are +2 and +4
(x+2)(x+4)=0
Now, two numbers will only multiply to give 0 is one or the other or both equal zero.
so now we have two more little equations to solve
either x+2=0 or x+4=0
.............x=-2 0r x=-4
The roots are -2 and -4
Now you can do your own one.
+118654 
