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Algebra / Linear functions Difficulty: Medium

In the linear function f , f0=8 and f1=12. Which equation defines f ?

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Explanation

Choice D is correct. Since f is a linear function, it can be defined by an equation of the form fx=ax+b, where a and b are constants. It's given that f0=8. Substituting 0 for x and 8 for fx in the equation fx=ax+b yields 8=a0+b, or 8=b. Substituting 8 for b in the equation fx=ax+b yields fx=ax+8. It's given that f1=12. Substituting 1 for x and 12 for fx in the equation fx=ax+8 yields 12=a1+8, or 12=a+8. Subtracting 8 from both sides of this equation yields a=4. Substituting 4 for a in the equation fx=ax+8 yields fx=4x+8. Therefore, an equation that defines f is fx=4x+8.

Choice A is incorrect and may result from conceptual or calculation errors.

Choice B is incorrect and may result from conceptual or calculation errors.

Choice C is incorrect and may result from conceptual or calculation errors.