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Solve the system of equations.

[tex]\[
\begin{array}{l}
y = 3x \\
y = x^2 - 10
\end{array}
\][/tex]

A. [tex]\((-2, -6)\)[/tex] and [tex]\((-5, -15)\)[/tex]

B. [tex]\((-2, -6)\)[/tex] and [tex]\((5, 15)\)[/tex]

C. [tex]\((2, 6)\)[/tex] and [tex]\((5, 15)\)[/tex]

D. [tex]\((2, 6)\)[/tex] and [tex]\((-5, -15)\)[/tex]


Sagot :

To solve the system of equations:
[tex]\[ y = 3x \][/tex]
[tex]\[ y = x^2 - 10 \][/tex]

we need to find the points where these two equations intersect. These intersection points are where the values of [tex]\(x\)[/tex] and [tex]\(y\)[/tex] satisfy both equations simultaneously.

### Step-by-Step Solution

1. Set the equations equal to each other:
Since both equations equal [tex]\( y \)[/tex], we can set them equal to each other:
[tex]\[ 3x = x^2 - 10 \][/tex]

2. Rearrange the equation:
Move all terms to one side to set the equation to 0:
[tex]\[ x^2 - 3x - 10 = 0 \][/tex]

3. Solve the quadratic equation:
We solve the quadratic equation [tex]\( x^2 - 3x - 10 = 0 \)[/tex] using the quadratic formula [tex]\( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \)[/tex], where [tex]\( a = 1 \)[/tex], [tex]\( b = -3 \)[/tex], and [tex]\( c = -10 \)[/tex].
[tex]\[ x = \frac{-(-3) \pm \sqrt{(-3)^2 - 4(1)(-10)}}{2(1)} \][/tex]
[tex]\[ x = \frac{3 \pm \sqrt{9 + 40}}{2} \][/tex]
[tex]\[ x = \frac{3 \pm \sqrt{49}}{2} \][/tex]
[tex]\[ x = \frac{3 \pm 7}{2} \][/tex]
This gives us two solutions for [tex]\( x \)[/tex]:
[tex]\[ x = \frac{3 + 7}{2} = 5 \][/tex]
[tex]\[ x = \frac{3 - 7}{2} = -2 \][/tex]

4. Find the corresponding [tex]\( y \)[/tex] values:
Substitute each [tex]\( x \)[/tex] value back into the first equation [tex]\( y = 3x \)[/tex] to find the corresponding [tex]\( y \)[/tex].

For [tex]\( x = 5 \)[/tex]:
[tex]\[ y = 3(5) = 15 \][/tex]
So, one point of intersection is [tex]\( (5, 15) \)[/tex].

For [tex]\( x = -2 \)[/tex]:
[tex]\[ y = 3(-2) = -6 \][/tex]
So, the other point of intersection is [tex]\( (-2, -6) \)[/tex].

### Conclusion

The points of intersection of the given system of equations are:
[tex]\[ (5, 15) \text{ and } (-2, -6) \][/tex]

Thus, the correct answer is:
[tex]\[ \boxed{B. (-2,-6) \text{ and } (5,15)} \][/tex]