Solve for x
(4^(3x))(x+1)=8(x+1)^(2x)
There is a typo error earlier and the error is corrected.
Hi,
1. Simplify, by applying rules of indices, till you obtain
8^(2x - 1) = (x + 1)^(2x - 1).
2. Take log (or natural) of both sides, from which one of the answers (1/2) would be obvious.
Thanks.
Cheers,
Wen Shih
Originally posted by wee_ws:Hi,
1. Simplify, by applying rules of indices, till you obtain
4^(2x - 1) = (x + 1)^(2x - 1).
2. Take log (or natural) of both sides, from which the answer (1/2) will be obvious.
Thanks.
Cheers,
Wen Shih
The answer of 1/2 does not seem to be correct both before and after the typo error is corrected.
Hi,
Starting with 8^(2x -1) = (x + 1)^(2x - 1)
=> (2x - 1) ln 8 = (2x - 1) ln (x + 1)
=> (2x - 1) ln (8/(x + 1)) = 0
=> 2x - 1 = 0 or 8/(x + 1) = 1
=> x = 1/2 or x = 7.
Thanks.
Cheers,
Wen Shih
Originally posted by wee_ws:Hi,
Let's verify, when x = 1/2:
LHS = (4^1.5)(1.5) = 12
RHS = 8(1.5) = 12.
Thanks.
Cheers,
Wen Shih
Thanks. The answer 1/2 is indeed correct. My bad for not verifying your answer.
However, the answer x = 7 is also another possible answer.
(4^(3x))(x+1)=8(x+1)^(2x)
(4^21)(8)= 8(8^14)
2^42=2^42
Strange, why is that there are two possible answers ?