SOLUTION: exponential equation how do u solve 25<sup>2x+3</sup> = 25<sup>5x-9</sup> next one 9<sup>8x-4</sup> = 81<sup>3x+6</sup>

Algebra ->  Trigonometry-basics -> SOLUTION: exponential equation how do u solve 25<sup>2x+3</sup> = 25<sup>5x-9</sup> next one 9<sup>8x-4</sup> = 81<sup>3x+6</sup>      Log On


   

Question 622899: exponential equation how do u solve 252x+3 = 255x-9 next one 98x-4 = 813x+6
Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
            252x+3 = 255x-9

Use the principle: The equation BA = BC is
equivalent to the equation A = C if B > 0 and B ≠ 1

            252x+3 = 255x-9

is equivalent to 

             2x+3 = 5x-9
               12 = 3x
                4 = x 

--------------------------------------------

             98x-4 = 813x+6

Write 81 as 92

             98x-4 = (92)3x+6

Multiply exponents on the right to remove the parentheses:

             98x-4 = 96x+12

Now we can use the principle: The equation BA = BC is
equivalent to the equation A = C if B > 0 and B ≠ 1

             98x-4 = 96x+12

is equivalent to 

             8x-4 = 6x+12
               2x = 16
                x = 8

Edwin