1, the general form of logarithmic function is y=logax, which is actually the inverse function of exponential function. The inverse function of two functions y = x = a y about the image with linear symmetry can be expressed as x = a y. ..
Therefore, there is a provision for A in the exponential function-A >; 0 and a≠ 1, different function diagrams will be formed for different sizes of a, and when a >, it is symmetrical about x axis; At 1, the larger a is, the closer the image is to the X axis, when 0
2. The sizes of two exponential functions or logarithmic functions can be compared by the monotonicity of the exponential function or logarithmic function. To find the monotone interval of function y=afx, we first need the monotone interval of fx, and then find the monotone interval of function y=afx according to the monotonicity of y=au. To find the monotone interval of function y=logafx, we first need the monotone interval of fx, and then find the monotone interval of function y=logafx according to the monotonicity of y=logau.
3. We can compare the sizes of two exponential or logarithmic functions through their monotonicity. To find the monotone interval of function y=afx, we first need the monotone interval of fx, and then find the monotone interval of function y=afx according to the monotonicity of y=au. To find the monotone interval of function y=logafx, we first need the monotone interval of fx, and then find the monotone interval of function y=logafx according to the monotonicity of y=logau.
Problem solving skills:
1, the idea of transformation is an important mathematical idea, and the logarithmic formula is closely related to the exponential formula. When solving related problems, the two forms often transform each other.
2. Skillfully use the formula: loga 1=0, logaa= 1, alogaM=M, logaan = n.
Sometimes logarithmic operation is more convenient than exponential operation, so the exponential expression can be transformed from exponential operation to logarithmic operation by taking logarithm.