Solve the following equation analytically 3ln 4x 7 15 Solv
Solve the following equation analytically. 3ln (4x + 7) = 15 Solve the following equation analytically. log_7 (x - 5) + log_7 (x + 1) = 1
Solution
Solution:
(6). 3ln(4x+7)= 15
divide by 3 on both side
ln(4x+7) = 5
Now
ln(4x+7) = lne5 ( lnaab = b lnaa)
4x +7 = e5
4x = e5-7
x = (e5-7) / 4
(15.)
log7 (x-5) + log7(x+1) =1
logA + logB = logAB
log7 ((x-5) (x+1)) = 1
log7 ((x-5) (x+1)) = log771
((x-5) (x+1)) = 7
x2-4x-5 =7
x2-4x-12 =0
(x-6) (x+2) =0
x= 6 and x=-2
Let\'s
plug x = -2 in below
log7 (x-5) + log7(x+1) =1
we get negative value in domain of log and that is not define
Now plug x = 2
log7 (x-5) + log7(x+1) =1
we can see x =6 varify above eqaution therefore
x= 6 is correct answer:
