SOLUTION: Someone please help me with it. Evaluate Log base2 (30) - log base2 (12) - log base2 (20)

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: Someone please help me with it. Evaluate Log base2 (30) - log base2 (12) - log base2 (20)      Log On


   

Question 962962: Someone please help me with it. Evaluate Log base2 (30) - log base2 (12) - log base2 (20)
Found 2 solutions by Fombitz, josmiceli:
Answer by Fombitz(32388) About Me  (Show Source):
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
+log%28+2%2C30+%29+-+log%28+2%2C12+%29+-+log%28+2%2C20+%29+
Use the rule:
+log%28+a+%29+-+log%28+b+%29+=+log%28%28+a%2Fb+%29%29+
+log%28+2%2C+%2830%2F12%29+%29+-+log%28+2%2C20+%29+
+log%28+2%2C+%285%2F2%29+%29+-+log%28+2%2C20+%29+
+log%28+2%2C+%285%2F%282%2A20%29%29+%29+
+log%28+2%2C+%281%2F8%29+%29+
Now I will say:
+y+=+log%28+2%2C+%281%2F8+%29%29+
+2%5Ey+=+1%2F8+
+2%5Ey+=+2%5E%28-3%29+
+y+=+-3+
Now I can say:
+log%28+2%2C+%281%2F8+%29%29+=+-3+