Michaela and Grace were trying to solve the equation:

[tex]\[ 4x^2 - 100 = 0 \][/tex]

Michaela said, "I'll factor the left-hand side of the equation as [tex]\((2x + 10)(2x - 10)\)[/tex] and solve using the zero product property."

Grace said, "I'll isolate the [tex]\(x^2\)[/tex] term by adding 100 and dividing by 4 on both sides of the equation. Then I'll solve by taking the square root."

Whose solution strategy would work?

Choose 1 answer:

A. Michaela's strategy
B. Grace's strategy
C. Both strategies
D. Neither strategy



Answer :

Both Michaela's and Grace's solution strategies work. Let's go through each strategy step-by-step to verify this.

### Michaela's Strategy:
1. Equation Setup:
[tex]\( 4x^2 - 100 = 0 \)[/tex]

2. Factoring:
Recognize that the equation can be factored as the difference of squares.
[tex]\[ 4x^2 - 100 = (2x)^2 - 10^2 = (2x + 10)(2x - 10) = 0 \][/tex]

3. Zero Product Property:
Apply the zero product property, which states that if the product of two factors is zero, then at least one of the factors must be zero.
[tex]\[ 2x + 10 = 0 \quad \text{or} \quad 2x - 10 = 0 \][/tex]

4. Solving Each Equation:
- For [tex]\( 2x + 10 = 0 \)[/tex]:
[tex]\[ 2x = -10 \implies x = -5 \][/tex]
- For [tex]\( 2x - 10 = 0 \)[/tex]:
[tex]\[ 2x = 10 \implies x = 5 \][/tex]

5. Solutions:
[tex]\[ x = -5 \quad \text{or} \quad x = 5 \][/tex]

### Grace's Strategy:
1. Equation Setup:
[tex]\( 4x^2 - 100 = 0 \)[/tex]

2. Isolating [tex]\( x^2 \)[/tex]:
Add 100 to both sides to isolate the [tex]\(x^2\)[/tex] term.
[tex]\[ 4x^2 = 100 \][/tex]

3. Dividing by 4:
Divide both sides by 4 to further isolate [tex]\(x^2\)[/tex].
[tex]\[ x^2 = 25 \][/tex]

4. Taking the Square Root:
Take the square root of both sides to solve for [tex]\( x \)[/tex], remembering to consider both positive and negative roots.
[tex]\[ x = \pm \sqrt{25} \][/tex]
[tex]\[ x = \pm 5 \][/tex]

5. Solutions:
[tex]\[ x = -5 \quad \text{or} \quad x = 5 \][/tex]

### Conclusion:
Both strategies correctly solve the equation [tex]\( 4x^2 - 100 = 0 \)[/tex]. Michaela's factoring method and Grace's isolating and square root method both yield the solutions:
[tex]\[ x = -5 \quad \text{or} \quad x = 5 \][/tex]
Thus, both Michaela's and Grace's solution strategies work.