Math Problem Statement

Solve the inequality: (x - 1)/(2x + 5) > (-3x)/(5 - 2x) - (-2x)/(2x - 5)

Solution

The inequality provided in the image is:

x12x+5>3x52x2x2x5\frac{x - 1}{2x + 5} > \frac{-3x}{5 - 2x} - \frac{-2x}{2x - 5}

To solve this inequality, let's proceed step by step:

Step 1: Simplify the right-hand side

We first need to combine the fractions on the right-hand side.

The right-hand side is:

3x52x2x2x5\frac{-3x}{5 - 2x} - \frac{-2x}{2x - 5}

Notice that 52x5 - 2x and 2x52x - 5 are negatives of each other:

52x=(2x5)5 - 2x = -(2x - 5)

Thus, we can rewrite the right-hand side as:

3x52x2x(52x)=3x52x+2x52x\frac{-3x}{5 - 2x} - \frac{-2x}{-(5 - 2x)} = \frac{-3x}{5 - 2x} + \frac{2x}{5 - 2x}

Combine the fractions:

3x+2x52x=x52x\frac{-3x + 2x}{5 - 2x} = \frac{-x}{5 - 2x}

Step 2: Rewrite the inequality

Now, the inequality becomes:

x12x+5>x52x\frac{x - 1}{2x + 5} > \frac{-x}{5 - 2x}

Step 3: Cross-multiply (taking into account sign changes)

To solve the inequality, we can cross-multiply. However, be careful: the sign of the inequality might change depending on the sign of the expressions 2x+52x + 5 and 52x5 - 2x.

  • 2x+52x + 5 is positive when x>52x > -\frac{5}{2}.
  • 52x5 - 2x is positive when x<52x < \frac{5}{2}.

So, we need to consider the intervals x<52x < -\frac{5}{2}, 52<x<52-\frac{5}{2} < x < \frac{5}{2}, and x>52x > \frac{5}{2}.

Case 1: x<52x < -\frac{5}{2}

In this case, both 2x+52x + 5 and 52x5 - 2x are negative, so we multiply by their absolute values and flip the inequality:

(x1)(52x)<x(2x+5)-(x - 1)(5 - 2x) < -x(2x + 5)

Simplifying this, we get:

(x1)(52x)>x(2x+5)(x - 1)(5 - 2x) > x(2x + 5)

Expanding both sides:

5x2x25+2x>2x2+5x5x - 2x^2 - 5 + 2x > 2x^2 + 5x

Combine like terms:

4x2+7x5>0-4x^2 + 7x - 5 > 0

Case 2: 52<x<52-\frac{5}{2} < x < \frac{5}{2}

In this interval, 2x+5>02x + 5 > 0 and 52x>05 - 2x > 0, so we do not flip the inequality:

(x1)(52x)>x(2x+5)(x - 1)(5 - 2x) > -x(2x + 5)

Expanding:

5x2x25+2x>2x25x5x - 2x^2 - 5 + 2x > -2x^2 - 5x

Combine like terms:

4x2+7x5>0-4x^2 + 7x - 5 > 0

This is the same quadratic as above.

Case 3: x>52x > \frac{5}{2}

Here, both 2x+5>02x + 5 > 0 and 52x<05 - 2x < 0, so we flip the inequality:

(x1)(52x)<x(2x+5)(x - 1)(5 - 2x) < -x(2x + 5)

Expanding:

5x2x25+2x<2x25x5x - 2x^2 - 5 + 2x < -2x^2 - 5x

This simplifies to:

4x2+7x5<0-4x^2 + 7x - 5 < 0

Conclusion

We now need to solve the quadratic inequality 4x2+7x5>0-4x^2 + 7x - 5 > 0 and 4x2+7x5<0-4x^2 + 7x - 5 < 0 in the respective intervals.

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Math Problem Analysis

Mathematical Concepts

Inequalities
Algebraic Manipulation
Quadratic Inequalities

Formulas

Simplifying algebraic fractions
Cross-multiplication
Solving quadratic inequalities

Theorems

Properties of inequalities
Quadratic inequality solution methods

Suitable Grade Level

Grades 10-12