SOLUTION: Given that log 5=0.6990 and log 7=0.8451, evaluate a) log 35 (b) log 2.8 (c) Given that N 0.8942=2.8, use your result in (b) above to find the value of N

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Given that log 5=0.6990 and log 7=0.8451, evaluate a) log 35 (b) log 2.8 (c) Given that N 0.8942=2.8, use your result in (b) above to find the value of N      Log On


   

Question 1202253: Given that log 5=0.6990 and log 7=0.8451, evaluate a) log 35 (b) log 2.8
(c) Given that N 0.8942=2.8, use your result in (b) above to find the value of N
Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
a start only
log%28%2835%29%29=log%28%285%2A7%29%29=log%28%285%29%29%2Blog%28%287%29%29, and soon you want to look for log%28%284%29%29 which is same as log%28%282%2A2%29%29.

Answer by ikleyn(52775) About Me  (Show Source):
You can put this solution on YOUR website!
.
Given that log 5=0.6990 and log 7=0.8451, evaluate
(a) log 35
(b) log 2.8
(c) Given that N 0.8942=2.8, use your result in (b) above to find the value of N
~~~~~~~~~~~~~~~~~


            In this my post,  I will solve  (a)  and  (b),  ONLY.

            I will not solve  (c)  in order for do not make a mess from this post. 


(a)  35 = 5*7;  therefore log(35) = log(5*7) = log(5) + log(7) = 0.6990 + 0.8451 = 1.541.    ANSWER



(b)  First, log(2) = log%28%2810%2F5%29%29 = log(10) - log(5) = 1 - 0.6990 = 0.301.

     Next, 2.8 = 14%2F5 = %287%2A2%29%2F5 = log(7) + log(2) - log(5) = 0.8451 + 0.301 - 0.6990 = 0.4471.  ANSWER

Solved.


///////////////////


By the way, what is written in your part (c), mathematically is UNREADABLE
and, THEREFORE, makes no sense.