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Basic Math/Adding functions - 11 grade algebra

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Expert: Josh - 1/24/2007


Question
trying to help my son and it has been too many years.  Given the functions f(x)=3x-4 & g(x)=2x+3.  Find (f+g)(x).

Is this 3x+4 + 2x+3 = 5x+7  ???

Answer
Hi Bob,

Yes, that's the idea.
(f+g)(x)=f(x)+g(x)
There is probably a typo though. If f(x)=3x-4, then, f(x)+g(x) should be 3x-4 + 2x+3 = 5x-1.

A related concept called composition of functions, written as f.g(x) or f o g(x), involves substituting the expression g(x) for x in the function f(x).

For example, if f(x)=x^2+1 and g(x)=2x-2, then, f.g(x)=(2x-2)^2+1 =4x^2-8x+5.

Regards

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Josh

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When I work through problems, I like to emphasize concepts which I believe are worth noting. I will try to answer questions in the following areas, but not at the advanced level. Algebra. Sequences & Series. Trigonometry. Functions & Graphs. Coordinate Geometry. Quadratic Polynomials. Exponential & Logarithms. Basic Calculus. Probability, Permutation and Combination. Mathematical Induction. Complex numbers. Physics problems.

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I have worked as a teaching assistant in college. My hope is that more people will share knowledge without boundary, give help without seeking recognition or monetary rewards.

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Bachelor degree in Engineering Science

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