Solve the Quadratic Equation: x²/4 + (2/3)x + 4/9} = 0

Quadratic Formula with Fractional Coefficients

Solve the following equation:

x24+23x+49=0 \frac{x^2}{4}+\frac{2}{3}x+\frac{4}{9}=0

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find X
00:04 Let's identify the coefficients
00:24 Let's use the roots formula
00:46 Let's substitute appropriate values according to the given data and solve
01:12 Let's calculate the square and products
01:29 A root of 0 is always equal to 0
01:45 When the root equals 0, there will be only one solution to the equation
02:10 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve the following equation:

x24+23x+49=0 \frac{x^2}{4}+\frac{2}{3}x+\frac{4}{9}=0

2

Step-by-step solution

To solve the quadratic equation x24+23x+49=0 \frac{x^2}{4}+\frac{2}{3}x+\frac{4}{9}=0 , we will use the quadratic formula:

The quadratic formula is given by:
x=b±b24ac2a x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

First, we identify the coefficients:
a=14 a = \frac{1}{4} , b=23 b = \frac{2}{3} , c=49 c = \frac{4}{9}

Now, we calculate the discriminant:
b24ac=(23)241449 b^2 - 4ac = \left(\frac{2}{3}\right)^2 - 4 \cdot \frac{1}{4} \cdot \frac{4}{9}

Calculating further:
b2=49 b^2 = \frac{4}{9}
4ac=41449=1636=49 4ac = 4 \cdot \frac{1}{4} \cdot \frac{4}{9} = \frac{16}{36} = \frac{4}{9}

Hence, the discriminant:
b24ac=4949=0 b^2 - 4ac = \frac{4}{9} - \frac{4}{9} = 0

Since the discriminant is 0, there is exactly one real solution. We apply the quadratic formula:
x=(23)±02×14 x = \frac{-\left(\frac{2}{3}\right) \pm \sqrt{0}}{2 \times \frac{1}{4}}

Simplify:
x=2312=232=43 x = \frac{-\frac{2}{3}}{\frac{1}{2}} = -\frac{2}{3} \cdot 2 = -\frac{4}{3}

Therefore, the solution to the problem is x=43 x = -\frac{4}{3} .

3

Final Answer

x=43 x=-\frac{4}{3}

Key Points to Remember

Essential concepts to master this topic
  • Identify coefficients: Match standard form ax² + bx + c = 0 carefully
  • Discriminant formula: b² - 4ac = (2/3)² - 4(1/4)(4/9) = 0
  • Verify solution: Substitute x = -4/3 back into original equation ✓

Common Mistakes

Avoid these frequent errors
  • Incorrectly calculating the discriminant with fractions
    Don't rush fraction arithmetic in b² - 4ac = wrong discriminant! Students often mess up (2/3)² or 4(1/4)(4/9), leading to wrong solutions or thinking there are two roots. Always compute each part carefully: (2/3)² = 4/9 and 4ac = 4/9.

Practice Quiz

Test your knowledge with interactive questions

a = Coefficient of x²

b = Coefficient of x

c = Coefficient of the independent number


what is the value of \( a \) in the equation

\( y=3x-10+5x^2 \)

FAQ

Everything you need to know about this question

Why is there only one solution when quadratics usually have two?

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When the discriminant equals zero (b² - 4ac = 0), the parabola touches the x-axis at exactly one point. This means there's one repeated root, not two different solutions.

How do I handle all these fractions without making mistakes?

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Work step-by-step and find common denominators when adding/subtracting fractions. For this problem: (2/3)² = 4/9 and 4ac = 4(1/4)(4/9) = 4/9, so they cancel out perfectly.

Can I multiply the entire equation by something to clear fractions first?

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Yes! Multiply by the LCD of all denominators (36 in this case). You'll get 9x² + 24x + 16 = 0, which is easier to work with using the quadratic formula.

How do I check if x = -4/3 is really correct?

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Substitute back: (4/3)24+23(4/3)+49 \frac{(-4/3)^2}{4} + \frac{2}{3}(-4/3) + \frac{4}{9} = 16/9489+49 \frac{16/9}{4} - \frac{8}{9} + \frac{4}{9} = 4989+49=0 \frac{4}{9} - \frac{8}{9} + \frac{4}{9} = 0

What if I get a different answer using factoring?

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This equation is a perfect square trinomial! If you multiply by 36 first, you get 9x² + 24x + 16 = (3x + 4)² = 0, giving x = -4/3. Both methods should give the same answer.

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