IDNLearn.com: Your one-stop destination for finding reliable answers. Ask your questions and get detailed, reliable answers from our community of experienced experts.

Which of the following are solutions to the equation below? Check all that apply.

[tex]\(4x^2 - 12x + 9 = 5\)[/tex]

A. [tex]\(x = \frac{\sqrt{5} + 3}{2}\)[/tex]

B. [tex]\(x = -\sqrt{4} - 3\)[/tex]

C. [tex]\(x = -\sqrt{5} + \frac{3}{2}\)[/tex]

D. [tex]\(x = \sqrt{5} + \frac{3}{2}\)[/tex]

E. [tex]\(x = \frac{-\sqrt{5} + 3}{2}\)[/tex]

F. [tex]\(x = \sqrt{4} - 3\)[/tex]


Sagot :

Let's solve the quadratic equation [tex]\( 4x^2 - 12x + 9 = 5 \)[/tex] for [tex]\( x \)[/tex].

1. Rewrite the equation in standard form:
[tex]\[ 4x^2 - 12x + 9 - 5 = 0 \implies 4x^2 - 12x + 4 = 0 \][/tex]

2. Factor the quadratic equation (if possible):
[tex]\[ 4x^2 - 12x + 4 = 0 \][/tex]
This can be immediately solved by recognizing it's a quadratic equation. To solve, we should find the roots using the quadratic formula, which is:
[tex]\[ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \][/tex]
Here, [tex]\( a = 4 \)[/tex], [tex]\( b = -12 \)[/tex], and [tex]\( c = 4 \)[/tex].

3. Substitute [tex]\( a \)[/tex], [tex]\( b \)[/tex], and [tex]\( c \)[/tex] into the quadratic formula:
[tex]\[ x = \frac{-(-12) \pm \sqrt{(-12)^2 - 4 \cdot 4 \cdot 4}}{2 \cdot 4} \][/tex]
[tex]\[ x = \frac{12 \pm \sqrt{144 - 64}}{8} \][/tex]
[tex]\[ x = \frac{12 \pm \sqrt{80}}{8} \][/tex]
[tex]\[ x = \frac{12 \pm 4 \sqrt{5}}{8} \][/tex]
[tex]\[ x = \frac{12}{8} \pm \frac{4 \sqrt{5}}{8} \][/tex]
[tex]\[ x = \frac{3}{2} \pm \frac{\sqrt{5}}{2} \][/tex]

4. Simplify the solutions found:
[tex]\[ x = \frac{3 + \sqrt{5}}{2} \quad \text{and} \quad x = \frac{3 - \sqrt{5}}{2} \][/tex]

Now, compare these solutions to the provided options:
- [tex]\( \boxed{\text{A.}\ x = \frac{\sqrt{5} + 3}{2}} \)[/tex]
- B. [tex]\( x = -\sqrt{4} - 3 = -2 - 3 = -5 \)[/tex]
- C. [tex]\( x = -\sqrt{5} + \frac{3}{2} \)[/tex]
- D. [tex]\( x = \sqrt{5} + \frac{3}{2} = \frac{\sqrt{5} + 3}{2} \)[/tex] (matches option A again)
- [tex]\( \boxed{\text{E.}\ x = \frac{-\sqrt{5} + 3}{2}} \)[/tex]
- F. [tex]\( x = \sqrt{4} - 3 = 2 - 3 = -1 \)[/tex]

From the given options, the solutions that apply are:
- [tex]\( \boxed{\text{A.}\ x = \frac{\sqrt{5} + 3}{2}} \)[/tex]
- [tex]\( \boxed{\text{E.}\ x = \frac{-\sqrt{5} + 3}{2}} \)[/tex]

Thus, the correct options are A and E.