SOLUTION: Use the equation y=x(squared)-3x-10 -compared to the graph of y=-3x(squared), does this graph open in the same direction or opposite? -find x-intercepts for the graph ----

Algebra ->  Algebra  -> Quadratic Equations and Parabolas  -> Quadratic Equation Customizable Word Problems -> SOLUTION: Use the equation y=x(squared)-3x-10 -compared to the graph of y=-3x(squared), does this graph open in the same direction or opposite? -find x-intercepts for the graph ----      Log On

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Question 2688: Use the equation y=x(squared)-3x-10
-compared to the graph of y=-3x(squared), does this graph open in the same direction or opposite?
-find x-intercepts for the graph
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could you please answer as soon as possible and please explain how you got your answer and why it is correct...thank you so much!

Answer by khwang(438) About Me  (Show Source):
You can put this solution on YOUR website!
y=x^2-3x-10 -compared to the graph of y=-3x^2,
does this graph open in the same direction or opposite?
-find x-intercepts for the graph

At first you should know how to type the squares correctly.
Use complete square to y=x^2-3x-10, we have
y = (x-3/2)^2 -10 -9/4 = (x-3/2)^2 -49/4 or
y + 49/4 = (x-3/2)^2
So, this parabola has vertex (3/2,-49/4) and open upward (since (x-3/2)^2 >=0)
Another graph y=-3x^2 has vertex (0,0) and open downward (since -3x^2 <=0)
Also, set y=0, in y=x^2-3x-10 =0,
By factoring x^2-3x-10 = (x-5)(x+2) =0, we have x=5 or -2.
So, y=x^2-3x-10 has two x-intercepts 5 ,-2.
Clearly, set y=0, in y=-3x^2, we have the x-intercept =0.
Graphs as below:
+graph%28+300%2C+200%2C+-2%2C+6%2C+-12%2C+5%2C+x%5E2-3x-10%2C+-3x%5E2%29+