Using y=3xy = 3^xy=3x as a substitution, show that 9x−3x+2−10=09^x - 3^{x+2} - 10 = 09x−3x+2−10=0 can be written as y2−9y−10=0y^2 - 9y - 10 = 0y2−9y−10=0.
Hence, show that the equation 9x−3x+2−10=09^x - 3^{x+2} - 10 = 09x−3x+2−10=0 has x=log310x = \log_3 10x=log310 as its only solution.
277 exam-style questions on Edexcel A Level Maths Exponentials and Logarithms, covering 14.1 Exponential Functions, 14.2 y = e^x, 14.3 Exponential Modelling, 14.4 Logarithms, 14.5 Laws of Logarithms, 14.6 Solving Equations using Logarithms, 14.7 Working with Natural Logarithms, and 14.8 Logarithms and Non-Linear Data. Each one has a worked solution and a mark scheme showing where the marks go.