Math Problem Statement

यदि समीकरण x^2 + kx - 5/4 का एक मूल 1/2 है, तो k का मान है

Solution

The problem you have shared seems to be a quadratic equation where we need to find the value of kk. Let's break it down:

The equation is in the form:

x2+kx54=0x^2 + kx - \frac{5}{4} = 0

It also states that one of the roots of this equation is 12\frac{1}{2}.

We can use the fact that if r1r_1 and r2r_2 are the roots of the quadratic equation ax2+bx+c=0ax^2 + bx + c = 0, then by Vieta's formulas:

  1. The sum of the roots, r1+r2r_1 + r_2, is given by ba-\frac{b}{a}.
  2. The product of the roots, r1×r2r_1 \times r_2, is given by ca\frac{c}{a}.

Here, we have:

  • a=1a = 1
  • b=kb = k
  • c=54c = -\frac{5}{4}
  • One of the roots r1=12r_1 = \frac{1}{2}

From the product of the roots, we know that:

r1×r2=car_1 \times r_2 = \frac{c}{a}

So:

12×r2=54\frac{1}{2} \times r_2 = -\frac{5}{4}

Solving this for r2r_2:

r2=54×21=52r_2 = -\frac{5}{4} \times \frac{2}{1} = -\frac{5}{2}

Now, using the sum of the roots formula:

r1+r2=bar_1 + r_2 = -\frac{b}{a}

Substituting the values:

12+(52)=k\frac{1}{2} + \left( -\frac{5}{2} \right) = -k

Simplifying:

1252=k\frac{1}{2} - \frac{5}{2} = -k

42=k-\frac{4}{2} = -k

k=2k = 2

So, the value of kk is 2.

Would you like more details on any part of this explanation? Let me know if you have any further questions!


Here are some related questions:

  1. How do we use the quadratic formula to find roots of a quadratic equation?
  2. What are the applications of Vieta's formulas in solving quadratic equations?
  3. Can we apply the same method to find the value of a different unknown in a quadratic equation?
  4. How would the result change if the root were a different fraction?
  5. What happens if the given root is negative?

Tip: Always check the conditions of the problem carefully, as small changes in the equation or roots can lead to very different solutions.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Vieta's Formulas

Formulas

Quadratic equation: ax^2 + bx + c = 0
Sum of roots: r1 + r2 = -b/a
Product of roots: r1 * r2 = c/a

Theorems

Vieta's Formulas

Suitable Grade Level

Grades 8-10