Solve the Quadratic Equation: x²/3 + x - 10/3 = 0 Step-by-Step

Quadratic Equations with Fractional Coefficients

Solve the following equation:

x23+x103=0 \frac{x^2}{3}+x-\frac{10}{3}=0

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:08 Let's find the value of X.
00:12 First, multiply everything by 3 to get rid of fractions.
00:23 Now, identify the coefficients of the equation.
00:35 Next, use the root formula to help us solve it.
00:59 Substitute the values from our problem and work through the solution.
01:24 Then, calculate the squares and the products we need.
01:46 Find the square root of forty-nine.
01:53 These are the two possible solutions, one with addition and one with subtraction.
02:11 And that's how we solve this problem!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve the following equation:

x23+x103=0 \frac{x^2}{3}+x-\frac{10}{3}=0

2

Step-by-step solution

To solve the equation x23+x103=0 \frac{x^2}{3} + x - \frac{10}{3} = 0 , we will take these steps:

  • Step 1: Clear the fractions by multiplying the entire equation by 3:
    3×x23+3×x3×103=0 3 \times \frac{x^2}{3} + 3 \times x - 3 \times \frac{10}{3} = 0 .
  • Step 2: Simplify to get:
    x2+3x10=0 x^2 + 3x - 10 = 0 .
  • Step 3: Identify coefficients for the quadratic formula where a=1 a = 1 , b=3 b = 3 , and c=10 c = -10 .
  • Step 4: Apply the quadratic formula:
    x=b±b24ac2a=3±324×1×(10)2×1 x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} = \frac{-3 \pm \sqrt{3^2 - 4 \times 1 \times (-10)}}{2 \times 1} .
  • Step 5: Compute under the square root:
    324×1×(10)=9+40=49 3^2 - 4 \times 1 \times (-10) = 9 + 40 = 49 .
  • Step 6: Calculate the square root of 49, which is 7.
  • Step 7: Substitute back to find the values of x:
    x=3±72 x = \frac{-3 \pm 7}{2} .
  • Step 8: Calculate the two possible solutions:
    For x1 x_1 : x=3+72=2 x = \frac{-3 + 7}{2} = 2 .
    For x2 x_2 : x=372=5 x = \frac{-3 - 7}{2} = -5 .

Therefore, the solutions to the equation are x1=2 x_1 = 2 and x2=5 x_2 = -5 .

Thus, the answer is: x1=2,x2=5 x_1=2, x_2=-5 .

3

Final Answer

x1=2,x2=5 x_1=2,x_2=-5

Key Points to Remember

Essential concepts to master this topic
  • Clear Fractions: Multiply entire equation by 3 to eliminate denominators
  • Quadratic Formula: Use x=b±b24ac2a x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} with a=1, b=3, c=-10
  • Verify Solutions: Substitute x=2 and x=-5 back: 43+2103=0 \frac{4}{3} + 2 - \frac{10}{3} = 0

Common Mistakes

Avoid these frequent errors
  • Forgetting to multiply all terms when clearing fractions
    Don't multiply just x23 \frac{x^2}{3} by 3 and leave x and 103 -\frac{10}{3} unchanged = wrong equation! This creates an unbalanced equation leading to incorrect solutions. Always multiply every single term by the same number when clearing fractions.

Practice Quiz

Test your knowledge with interactive questions

a = coefficient of x²

b = coefficient of x

c = coefficient of the constant term


What is the value of \( c \) in the function \( y=-x^2+25x \)?

FAQ

Everything you need to know about this question

Why multiply by 3 instead of working with fractions directly?

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Multiplying by 3 eliminates all fractions at once, giving you the cleaner equation x2+3x10=0 x^2 + 3x - 10 = 0 . This makes factoring or using the quadratic formula much easier!

Can I factor this quadratic instead of using the formula?

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Yes! After clearing fractions, you get x2+3x10=0 x^2 + 3x - 10 = 0 , which factors as (x2)(x+5)=0 (x-2)(x+5) = 0 . Both methods give the same answers: x = 2 and x = -5.

How do I know which number to multiply by to clear fractions?

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Look at all the denominators in your equation. The least common multiple of all denominators is your multiplier. Here, we only have denominator 3, so multiply by 3.

What if I get a negative discriminant?

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A negative discriminant means no real solutions exist. In this problem, b24ac=9+40=49 b^2 - 4ac = 9 + 40 = 49 , which is positive, so we have two real solutions.

Do I always get two solutions for quadratic equations?

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Not always! You get two different solutions when the discriminant is positive, one repeated solution when it equals zero, and no real solutions when it's negative.

How can I check my solutions are correct?

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Substitute each solution back into the original equation. For x = 2: 43+2103=0 \frac{4}{3} + 2 - \frac{10}{3} = 0 ✓. For x = -5: 2535103=0 \frac{25}{3} - 5 - \frac{10}{3} = 0

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