11. Take the logarithm, base X. a² - ab = 10 Since we are given that b = a - 2, we can substitute for b to get a² - a(a -2) = 10 a² - a² + 2a = 10 . . . . . eliminate parentheses a = 5 . . . . . . . . . . . . . . simplify, divide by 2
_____ Check: a² = 5² = 25 ab = 5·3 = 15 X^25/X^15 = X^10 . . . . . the answer works