Math, asked by tssuyambulingam, 1 year ago

25^(x-1)
=5^(2x-1)-100
find x please



tssuyambulingam: what happened im sorry
kaushikravikant: look at RHS plzz
tssuyambulingam: its5^(2x-1)
kaushikravikant: okkkkk
tssuyambulingam: what happened
kaushikravikant: after solving it,my x is going to be cancelled out
tssuyambulingam: try it once pls
kaushikravikant: your question's statement is false.plzz type clear statement
bhalaraneha: you know the answer?
kaushikravikant: I can try,match the answer

Answers

Answered by bhalaraneha
533
      25^x-1 = 5^(2x-1) - 100
⇒ 5^2x-2 = 5^(2x-1) - 100
⇒ 5^2x-2 - 5^2x-1 = -100
⇒ 5^2x [ 5^-2 - 5^-1] = - 100
⇒ 5^2x [ 1  -  1 ]  = - 100
             25    5
⇒ 5^2x [ 1 - 5]  = - 100
               25
⇒ 5^2x [ -4 ] = - 100
              25
⇒ 5^2x [-4] = -100 * 25
⇒ 5^2x = 100 * 25     [ - * - = +]
                  4 
⇒ 5^2x = 625
⇒ 5^2x  = 5^4 
so, ⇒  2x = 4
      ⇒  x = 2

tssuyambulingam: but i cant understand the 4th step
bhalaraneha: when you do 5*5=25 but here the -square so.
tssuyambulingam: ok thanks
bhalaraneha: now understand?
tssuyambulingam: yes akka
bhalaraneha: :)
tssuyambulingam: what
Answered by kvnmurty
385
we need to bring together the terms containing x.  Then constant terms on the other side.  Then simplify by performing the addition/subtraction/multiplication.

25^{x-1}=5^{2x-1}-100\\\\=>\ (5^2)^{x-1}=5^{2x-1}\ -2^2*5^2\\\\=>\ 5^{2x-2}-5^{2x-1}\ = - 2^2*5^2\\\\=>\  5^{2x-2}*[ 1-5^1 ]=-2^2*5^2\\\\=>\  5^{2x-2}*-4=-4*5^2\\\\=>\  2x-2=2\\\\x=2

done.
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