Solve the following quadratic equations and find the discriminants: 1) 2x^2 + 7x + 3 = 0, 2) x^2 - 8x + 16 = 0, 3) 2x^2 - 4x + 5 = 0.

Question image

Understand the Problem

The question involves solving quadratic equations using the quadratic formula and calculating their discriminants (D) for three different quadratic equations.

Answer

1) $x_1 = -\frac{1}{2}, x_2 = -3$ 2) $x = 4$ 3) No real roots
Answer for screen readers
  1. Roots: $x_1 = -\frac{1}{2}, x_2 = -3$
  2. Root: $x = 4$
  3. No real roots

Steps to Solve

  1. Calculate the Discriminant (D) for the First Equation The first equation is $2x^2 + 7x + 3 = 0$. The discriminant is calculated as follows: $$ D = b^2 - 4ac $$ Here, $a = 2$, $b = 7$, and $c = 3$. Thus, $$ D = 7^2 - 4 \cdot 2 \cdot 3 = 49 - 24 = 25 $$

  2. Determine the Roots for the First Equation Now use the quadratic formula: $$ x = \frac{-b \pm \sqrt{D}}{2a} $$ Substituting in the values: $$ x_{1,2} = \frac{-7 \pm \sqrt{25}}{2 \cdot 2} = \frac{-7 \pm 5}{4} $$ This leads to two potential solutions: $$ x_1 = \frac{-2}{4} = -\frac{1}{2} $$ $$ x_2 = \frac{-12}{4} = -3 $$

  3. Calculate the Discriminant (D) for the Second Equation The second equation is $x^2 - 8x + 16 = 0$. Here, $a = 1$, $b = -8$, and $c = 16$. Calculate the discriminant: $$ D = (-8)^2 - 4 \cdot 1 \cdot 16 = 64 - 64 = 0 $$ Since $D = 0$, this indicates one repeated root.

  4. Determine the Root for the Second Equation Using the quadratic formula, we find: $$ x = \frac{-(-8) \pm \sqrt{0}}{2 \cdot 1} = \frac{8}{2} = 4 $$ Thus, the root is $x = 4$.

  5. Calculate the Discriminant (D) for the Third Equation The third equation is $2x^2 - 4x + 5 = 0$. Here, $a = 2$, $b = -4$, and $c = 5$. The discriminant is: $$ D = (-4)^2 - 4 \cdot 2 \cdot 5 = 16 - 40 = -24 $$ A negative discriminant indicates no real roots.

  1. Roots: $x_1 = -\frac{1}{2}, x_2 = -3$
  2. Root: $x = 4$
  3. No real roots

More Information

The quadratic formula helps find the roots even for complex solutions. A discriminant of zero means one root, while a negative discriminant indicates complex roots.

Tips

  • Forgetting to apply signs correctly when substituting values into the quadratic formula.
  • Miscalculating the discriminant; be cautious with the order of operations.
  • Not simplifying square roots or fractions completely.

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