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Function Input and Output. Lesson 2.1. 1. 4. 3. -3. 3. 1. The Magic Box. Consider a box that receives numbers in the top And alters them somehow and sends a (usually) different number out the spout. Today we look at the mathematical way of talking about the "rule".
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Function Input and Output Lesson 2.1
1 4 3 -3 3 1 The Magic Box • Consider a box that receives numbers in the top • And alters them somehow and sends a (usually) different number out the spout Today we look at the mathematical way of talking about the "rule" For each of the number combinations, can you figure out the "rule" which alters the number?
The Magic Box • Consider a box that receives numbers in the top • And alters them somehow and sends a (usually) different number out the spout
Input Value Output value Output Values • Output Value Evaluating the Function • Substitute the input value for every instance of the independentvariable in the function f(x)
Evaluating a Function • Given • Determine the value of the function h when x = 2 h(2) = ? • Determine h(-4)
Evaluating a Function • Calculator can evaluate functions • Also possible to evaluate for symbolic values of the independent variable
Independent Variable Dependent variable Finding Input Values • Consider the function as a box with a funneland spout … • What if we knew what was comingout and wished to know what went in that gave that result h(x)
Finding Input Values • Try using the “solve ( )” command on your calculator Press Diamond,Enter to force decimal answer
Finding Input Values • Given g(x) = x2 – 2x + 4 g(x) = 12 x = ? • Create an equation using the formula and the output 12 = x2 – 2x + 4 • Solve for all possible values of x which make that statement true
Possible Solution Strategies • Algebraic • factor the quadratics • Look at tables of values • Graph the function • create a horizontal line (i.e. at y = 4.4) • note the intersection • Use the solve command on the calculator
For You to Try • Try together in class on page 64 • Ex 8, 9 • Assignment • Page 66 • Exercises 3, 5, 10, 13, 15, 19, 25, 29, 31, 35, 37