Math Problem Statement

Find the set of values of the constant a for which the line y = 2 - 5x intersects the curve y = x^2 + ax + 18 at two points. Also, find the range of values of m for which the straight line y = mx - 5 intersects the curve y = x^2 - 1 in two distinct points.

Solution

Let's solve both of these problems step by step:

2. Find the set of values of the constant aa for which the line y=25xy = 2 - 5x intersects the curve y=x2+ax+18y = x^2 + ax + 18 at two points.

Step 1: Set the equations equal

To find the points of intersection, set the line equation equal to the curve equation: 25x=x2+ax+182 - 5x = x^2 + ax + 18

Step 2: Rearrange the equation

Move all terms to one side to form a quadratic equation: x2+ax+185x2=0x^2 + ax + 18 - 5x - 2 = 0 Simplify: x2+(a5)x+16=0x^2 + (a - 5)x + 16 = 0

Step 3: Analyze for two intersection points

For the line to intersect the curve at two points, the quadratic equation must have two distinct real roots. This means the discriminant must be positive. The discriminant Δ\Delta for a quadratic equation ax2+bx+c=0ax^2 + bx + c = 0 is given by: Δ=b24ac\Delta = b^2 - 4ac For our quadratic equation x2+(a5)x+16=0x^2 + (a - 5)x + 16 = 0, the discriminant becomes: Δ=(a5)24(1)(16)\Delta = (a - 5)^2 - 4(1)(16) Simplify: Δ=(a5)264\Delta = (a - 5)^2 - 64 For two distinct real roots, Δ>0\Delta > 0: (a5)264>0(a - 5)^2 - 64 > 0 (a5)2>64(a - 5)^2 > 64 Taking square roots: a5>8|a - 5| > 8 This gives two inequalities: a5>8ora5<8a - 5 > 8 \quad \text{or} \quad a - 5 < -8 Solve each inequality: a>13ora<3a > 13 \quad \text{or} \quad a < -3

Thus, the set of values of aa is: a<3ora>13a < -3 \quad \text{or} \quad a > 13


3. Find the range of values of mm for which the straight line y=mx5y = mx - 5 intersects the curve y=x21y = x^2 - 1 in two distinct points.

Step 1: Set the equations equal

Set the equation of the line equal to the equation of the curve: mx5=x21mx - 5 = x^2 - 1

Step 2: Rearrange the equation

Move all terms to one side to form a quadratic equation: x2mx+(1+5)=0x^2 - mx + (-1 + 5) = 0 Simplify: x2mx+4=0x^2 - mx + 4 = 0

Step 3: Analyze for two distinct points

For two distinct points of intersection, the discriminant of this quadratic equation must be positive. The discriminant Δ\Delta for x2mx+4=0x^2 - mx + 4 = 0 is: Δ=(m)24(1)(4)\Delta = (-m)^2 - 4(1)(4) Simplify: Δ=m216\Delta = m^2 - 16 For two distinct points, Δ>0\Delta > 0: m216>0m^2 - 16 > 0 Solve: m2>16m^2 > 16 Taking square roots: m>4|m| > 4 This gives two inequalities: m>4orm<4m > 4 \quad \text{or} \quad m < -4

Thus, the range of values of mm is: m<4orm>4m < -4 \quad \text{or} \quad m > 4


Would you like more details on any of these steps or further clarifications?

Here are 5 related questions you can explore:

  1. What happens if the discriminant is zero in the quadratic equations?
  2. How can you determine the points of intersection once you have the discriminant conditions?
  3. How do you find the vertex of a parabola given in quadratic form?
  4. What is the geometrical interpretation of discriminant conditions for curves and lines?
  5. How do higher-degree curves (like cubic equations) intersect with lines?

Tip: When solving problems involving intersections between curves and lines, always start by simplifying the equations and analyzing the discriminant of the resulting quadratic.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Discriminant
Intersection of Curves and Lines

Formulas

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

Theorems

Quadratic Formula
Condition for two distinct roots (Δ > 0)

Suitable Grade Level

Grades 9-12