Q. Given f(x)=−x+3 and g(x)=21x2−1, which is a solution to f(x)=g(x)A) −2B) −1C) 1D) 2
Set Equation Equal: To find the solution to f(x)=g(x), we need to set the two functions equal to each other and solve for x. So, we have the equation −x+3=(21)x2−1.
Form Quadratic Equation: First, let's move all terms to one side of the equation to set it to zero and form a quadratic equation.We add x and subtract 3 from both sides to get:(21)x2+x−4=0.
Eliminate Fraction: To make the equation easier to solve, we can multiply every term by 2 to get rid of the fraction:2×(21)x2+2×x−2×4=0×2,which simplifies to:x2+2x−8=0.
Factor Quadratic Equation: Now, we need to factor the quadratic equation, if possible.The factors of −8 that add up to 2 are 4 and −2.So, we can write the equation as:(x+4)(x−2)=0.
Apply Zero Product Property: Next, we apply the zero product property, which states that if a product of two factors is zero, then at least one of the factors must be zero.So, we set each factor equal to zero:x+4=0 or x−2=0.
Solve for x: Solving each equation for x gives us the possible solutions: x=−4 or x=2.
Check Answer Choices: We need to check which of these solutions is given in the answer choices.The choices are A) −2, B) −1, C) 1, D) 2.Only x=2 is in the answer choices, so x=−4 is not a valid option for this problem.
Verify Solution: Finally, we can verify that x=2 is indeed a solution by substituting it back into the original equations f(x) and g(x) to see if they are equal.For f(x), we have f(2)=−2+3=1.For g(x), we have g(2)=(21)(2)2−1=(21)(4)−1=2−1=1.Since f(2)=g(2), x=2 is a solution to f(x)=g(x).