Math Problem Statement

a/(x-b)+b/(x-a)=2 solve it by quadratic formula

Solution

We are tasked with solving the equation:

axb+bxa=2\frac{a}{x-b} + \frac{b}{x-a} = 2

Step 1: Combine the fractions

To combine the two fractions, we need a common denominator. The common denominator will be (xb)(xa)(x-b)(x-a). Thus, we rewrite the equation as:

a(xa)(xb)(xa)+b(xb)(xb)(xa)=2\frac{a(x-a)}{(x-b)(x-a)} + \frac{b(x-b)}{(x-b)(x-a)} = 2

Step 2: Simplify the equation

Now, combine the numerators on the left side:

a(xa)+b(xb)(xb)(xa)=2\frac{a(x-a) + b(x-b)}{(x-b)(x-a)} = 2

Distribute aa and bb in the numerators:

a(x)a2+b(x)b2(xb)(xa)=2\frac{a(x) - a^2 + b(x) - b^2}{(x-b)(x-a)} = 2

Combine like terms:

(a+b)x(a2+b2)(xb)(xa)=2\frac{(a+b)x - (a^2 + b^2)}{(x-b)(x-a)} = 2

Step 3: Eliminate the denominator

To eliminate the denominator, multiply both sides of the equation by (xb)(xa)(x-b)(x-a):

(a+b)x(a2+b2)=2(xb)(xa)(a+b)x - (a^2 + b^2) = 2(x-b)(x-a)

Step 4: Expand both sides

First, expand the right side:

(xb)(xa)=x2(a+b)x+ab(x-b)(x-a) = x^2 - (a+b)x + ab

Thus, the equation becomes:

(a+b)x(a2+b2)=2(x2(a+b)x+ab)(a+b)x - (a^2 + b^2) = 2(x^2 - (a+b)x + ab)

Now expand the right side:

(a+b)x(a2+b2)=2x22(a+b)x+2ab(a+b)x - (a^2 + b^2) = 2x^2 - 2(a+b)x + 2ab

Step 5: Rearrange the equation

Move all terms to one side:

0=2x22(a+b)x+2ab(a+b)x+(a2+b2)0 = 2x^2 - 2(a+b)x + 2ab - (a+b)x + (a^2 + b^2)

Combine like terms:

0=2x2(2a+2b+a+b)x+2ab+a2+b20 = 2x^2 - (2a + 2b + a + b)x + 2ab + a^2 + b^2

Simplify the coefficients:

0=2x2(3a+3b)x+2ab+a2+b20 = 2x^2 - (3a + 3b)x + 2ab + a^2 + b^2

Step 6: Solve using the quadratic formula

This is now a quadratic equation in the form Ax2+Bx+C=0Ax^2 + Bx + C = 0:

2x2(3a+3b)x+(a2+b2+2ab)=02x^2 - (3a + 3b)x + (a^2 + b^2 + 2ab) = 0

We can solve this using the quadratic formula:

x=B±B24AC2Ax = \frac{-B \pm \sqrt{B^2 - 4AC}}{2A}

Where A=2A = 2, B=(3a+3b)B = -(3a + 3b), and C=a2+b2+2abC = a^2 + b^2 + 2ab.

Substitute these values into the quadratic formula:

x=3a+3b±(3a+3b)24(2)(a2+b2+2ab)2(2)x = \frac{3a + 3b \pm \sqrt{(3a + 3b)^2 - 4(2)(a^2 + b^2 + 2ab)}}{2(2)}

Simplify the discriminant:

(3a+3b)2=9a2+18ab+9b2(3a + 3b)^2 = 9a^2 + 18ab + 9b^2

Now calculate the discriminant:

Δ=9a2+18ab+9b28(a2+b2+2ab)\Delta = 9a^2 + 18ab + 9b^2 - 8(a^2 + b^2 + 2ab)

Δ=9a2+18ab+9b28a28b216ab\Delta = 9a^2 + 18ab + 9b^2 - 8a^2 - 8b^2 - 16ab

Δ=a2+2ab+b2\Delta = a^2 + 2ab + b^2

Thus, the discriminant simplifies to:

Δ=(a+b)2\Delta = (a + b)^2

So the quadratic formula becomes:

x=3a+3b±(a+b)4x = \frac{3a + 3b \pm (a + b)}{4}

Step 7: Solve for the two possible values of xx

Now we have two cases to solve:

Case 1: ++

x=3a+3b+(a+b)4=4a+4b4=a+bx = \frac{3a + 3b + (a + b)}{4} = \frac{4a + 4b}{4} = a + b

Case 2: -

x=3a+3b(a+b)4=2a+2b4=a+b2x = \frac{3a + 3b - (a + b)}{4} = \frac{2a + 2b}{4} = \frac{a + b}{2}

Final Solution:

The two possible solutions for xx are:

x=a+borx=a+b2x = a + b \quad \text{or} \quad x = \frac{a + b}{2}

Would you like further clarification on any of the steps? Here are some related questions for exploration:

  1. How do you handle the case when the discriminant is zero?
  2. What happens if a=ba = b in this equation?
  3. How would you solve the same equation using a different method, such as substitution?
  4. What are some real-life scenarios where this type of equation might occur?
  5. How does the quadratic formula help in finding roots of any quadratic equation?

Tip: When solving quadratic equations, always check if the discriminant (Δ\Delta) is a perfect square, as this helps identify if the roots are real or complex.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Rational Expressions

Formulas

Quadratic formula: x = (-B ± √(B² - 4AC)) / 2A

Theorems

Quadratic formula

Suitable Grade Level

Grades 10-12