y=x2+4x−21The given equation represents a parabola in the xy-plane. Which of the following equivalent forms of the equation displays the x intercepts of the parabola as constants or coefficients?Choose 1 answer:(A) y=(x−3)(x+7)(B) y=x(x+4)−21(C) y=(x+2)2−25(D) y+24=(x+1)(x+3)
Q. y=x2+4x−21The given equation represents a parabola in the xy-plane. Which of the following equivalent forms of the equation displays the x intercepts of the parabola as constants or coefficients?Choose 1 answer:(A) y=(x−3)(x+7)(B) y=x(x+4)−21(C) y=(x+2)2−25(D) y+24=(x+1)(x+3)
Factor Quadratic Equation: To find the x-intercepts of the parabola, we need to factor the quadratic equation if possible. The given equation is y=x2+4x−21. We will look for two numbers that multiply to −21 and add up to 4.
Identify Correct Factored Form: The two numbers that satisfy these conditions are 7 and −3 because 7×(−3)=−21 and 7+(−3)=4. Therefore, we can factor the quadratic equation as y=(x−3)(x+7).
Confirm Matching Choice (A): Now we will check the answer choices to see which one matches the factored form of the equation. The factored form should directly show the x-intercepts as constants or coefficients.
Review Other Choices: Choice (A) y=(x−3)(x+7) matches the factored form we found, which displays the x-intercepts of the parabola as constants or coefficients. The x-intercepts are x=3 and x=−7.
Choice (B) Analysis: We will quickly review the other choices to confirm that they do not display the x-intercepts in the same clear manner as choice (A).
Choice (C) Analysis: Choice (B) y=x(x+4)−21 does not display the x-intercepts as constants or coefficients in a factored form.
Choice (D) Analysis: Choice (C) y=(x+2)2−25 is in vertex form and does not display the x-intercepts as constants or coefficients.
Choice (D) Analysis: Choice (C) y=(x+2)2−25 is in vertex form and does not display the x-intercepts as constants or coefficients.Choice (D) y+24=(x+1)(x+3) is not in the standard form of a quadratic equation and does not display the x-intercepts as constants or coefficients.
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