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Sia

Question
Math
Posted 10 months ago

Ali and Akari were trying to solve the equation:
(x1)(x7)=5
(x-1)(x-7)=5


Ali said, "I'll multiply (x1)(x7)(x-1)(x-7) and rewrite the equation as x28x+7=5x^{2}-8 x+7=5. Then I'll subtract 5 from both sides, and use the quadratic formula with a=1,b=8a=1, b=-8, and c=2c=2."

Akari said, "The left-hand side is factored, so I'll use the zero product property."

Whose solution strategy would work?
Choose 1 answer:
(A) Only Ali's
(B) Only Akari's
(C) Both
(D) Neither
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Answer from Sia
Posted 10 months ago
Solution by Steps
step 2
Ali's method involves expanding the left side to get x28x+7=5x^2 - 8x + 7 = 5. Then, he subtracts 5 from both sides to get x28x+2=0x^2 - 8x + 2 = 0. He plans to use the quadratic formula with a=1,b=8a=1, b=-8, and c=2c=2. However, Ali made a mistake in the constant term; it should be +75=+2+7 - 5 = +2, not c=2c=2
step 3
Akari's method involves using the zero product property. To do this, we first subtract 5 from both sides to get (x1)(x7)5=0(x-1)(x-7) - 5 = 0, which simplifies to (x1)(x7)=5(x-1)(x-7) = 5. Then, we set each factor equal to zero after moving 5 to the other side
step 4
Both methods will lead to the correct solutions for xx if applied correctly. Ali's mistake is in the constant term, but the method itself is sound. Akari's method is also correct
[1] Answer
C
Key Concept
Quadratic Equations
Explanation
Both factoring and using the quadratic formula are valid methods to solve quadratic equations. Ali's approach is correct except for the arithmetic error in determining the constant term. Akari's approach is also correct as it uses the zero product property.

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