Math Problem Statement

solve 5B 2

Show algebraically that the line y = kx + 5 intersects the parabola y = x^2 + 2 twice for all values of k.

Solution

It seems like you are working on question 5 from the image. The problem asks to:

Show algebraically that the line y=kx+5y = kx + 5 intersects the parabola y=x2+2y = x^2 + 2 twice for all values of kk.

Let's go through the solution step-by-step.

1. Setting the two equations equal:

We need to find where the line y=kx+5y = kx + 5 intersects the parabola y=x2+2y = x^2 + 2. So we set the two equations equal to each other:

kx+5=x2+2kx + 5 = x^2 + 2

2. Rearranging the equation:

Rearrange this to form a quadratic equation:

x2kx+25=0x^2 - kx + 2 - 5 = 0 x2kx3=0x^2 - kx - 3 = 0

3. Solving the quadratic:

The quadratic equation is now x2kx3=0x^2 - kx - 3 = 0. The discriminant of a quadratic equation ax2+bx+c=0ax^2 + bx + c = 0 is given by Δ=b24ac\Delta = b^2 - 4ac. For the quadratic to have two real solutions, the discriminant must be positive or zero (Δ0\Delta \geq 0).

Here, a=1a = 1, b=kb = -k, and c=3c = -3. So, the discriminant is:

Δ=(k)24(1)(3)\Delta = (-k)^2 - 4(1)(-3) Δ=k2+12\Delta = k^2 + 12

4. Analyzing the discriminant:

Since Δ=k2+12\Delta = k^2 + 12, this value is always greater than zero for all values of kk (since k20k^2 \geq 0 and 12 is positive). This means that the quadratic equation has two distinct real solutions for any value of kk.

Conclusion:

The line y=kx+5y = kx + 5 will always intersect the parabola y=x2+2y = x^2 + 2 twice, regardless of the value of kk.

Would you like any further clarification or details on this? Here are some related questions you might want to explore:

  1. Can the line ever be tangent to the parabola?
  2. What happens to the intersection points when k=0k = 0?
  3. Can we solve for the exact intersection points for a specific kk?
  4. How does the slope kk affect the steepness of the line and its intersections?
  5. Could we solve this problem using graphical methods?

Tip: Always analyze the discriminant of a quadratic equation to determine the number of solutions.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Parabolas

Formulas

Quadratic equation: ax^2 + bx + c = 0
Discriminant formula: Δ = b^2 - 4ac

Theorems

Quadratic discriminant theorem

Suitable Grade Level

Grades 10-12