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Math

Math Snap

PROBLEM

5 Consider the functions PP and QQ, defined as shown.
P(x)=x2+7x14Q(x)=3x+10\begin{array}{l} P(x)=x^{2}+7 x-14 \\ Q(x)=-3 x+10 \end{array} In the xyx y-coordinate plane, what are the coordinates of the points at which the graphs of the equations y=P(x)y=P(x) and y=Q(x)y=Q(x) intersect?
Explain how you determined your answer.
Enter your answer and your explanation in the space provided.

STEP 1

What is this asking?
Where do the parabolas y=x2+7x14y = x^2 + 7x - 14 and y=3x+10y = -3x + 10 cross?
Watch out!
Don't forget there might be two crossing points!

STEP 2

1. Set up the equation
2. Solve for xx
3. Solve for yy

STEP 3

Alright, so we want to find where these two parabolas meet, which means they'll have the same xx and yy values at those points.
Since both equations are already solved for yy, let's set them equal to each other!
This gives us x2+7x14=3x+10x^2 + 7x - 14 = -3x + 10.
This is where the magic happens!

STEP 4

Now, let's rewrite the equation to make it easier to solve.
We want it to look like a standard quadratic equation, which has the form ax2+bx+c=0ax^2 + bx + c = 0.
So, let's add 3x3x to both sides of our equation.
This gives us x2+10x14=10x^2 + 10x - 14 = 10.
Remember, we're adding 3x3x to both sides to keep the equation balanced!

STEP 5

Next, let's subtract 1010 from both sides to get everything on one side.
This gives us x2+10x24=0x^2 + 10x - 24 = 0.
Awesome! Now we have a nice, clean quadratic equation.

STEP 6

Time to solve for xx!
We can do this by factoring.
We're looking for two numbers that multiply to 24-24 and add up to 1010.
Those numbers are 1212 and 2-2.
So, we can rewrite our equation as (x+12)(x2)=0(x + 12)(x - 2) = 0.

STEP 7

Now, if (x+12)(x2)=0(x + 12)(x - 2) = 0, then either x+12=0x + 12 = 0 or x2=0x - 2 = 0.
This gives us two possible solutions for xx: x=12x = -12 and x=2x = 2.
Two solutions?
That means our parabolas cross at two points!

STEP 8

We've got our xx values, so now we need to find the corresponding yy values.
Let's use the simpler equation, y=3x+10y = -3x + 10, to do this.

STEP 9

For x=12x = -12, we have y=3(12)+10=36+10=46y = -3 \cdot (-12) + 10 = 36 + 10 = 46.
So, one intersection point is (12,46)(-12, 46).

STEP 10

For x=2x = 2, we have y=32+10=6+10=4y = -3 \cdot 2 + 10 = -6 + 10 = 4.
So, the other intersection point is (2,4)(2, 4).

SOLUTION

The graphs intersect at the points (12,46)(-12, 46) and (2,4)(2, 4).

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