LOGARITHMIC FUNCTIONS Solving Logarithmic Equations (Page 3 of 4)

Next we will solve the equation LOGbase2(x+5) = 3-LOGbase2(x-2) using the x-intercept method. First set the equation equal to zero: LOGbase2(x+5)-3+LOGbase2(x-2) = 0. Consider the expression on the left side of the equation to be the function f(x) = LOGbase2(x+5)-3+LOGbase2(x-2). To use the calculator, the change of base formula must be used to convert the base 2 logarithms to common or natural logarithms. We will use base 10: f(x) = log(x+5)/log2-3+log(x-2)/log2.

Enter this expression as Y1.

 Y= key. (Clear the previous functions)

 LOG key. X,T,theta,n key. Plus key. 5 Right parenthesis key. Divide key. LOG key. 2 Right parenthesis key. Minus key. 3
 Plus key. LOG key. X,T,theta,n key. Minus key. 2 Right parenthesis key. Divide key. LOG key. 2 Right parenthesis key.

 Calculator screen image.
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