Michael H. answered 03/24/20
High School Math, Physics, Computer Science & SAT/GRE/AP/PRAXIS Prep
Use the definition of logarithm:
logb(x) = c is the same thing as x = bc:
2x +17 = 72
Now solve for x:
2x +17 = 49
2x = 49 - 17 = 32
x = 32 / 2 = 16
Check:
log7(2x + 17) = log7(2(16) + 17) = log7(32 + 17) = log7(49) = log7(72) = 2*log7(7) = 2*1 = 2.