Question

Find x if 2^ (x + 5) = 4^ (x-1)​

Answer 1

Answer:

$\implies 2^{(x+5)} = 4^{(x-1)}\\\\\\\text{Expressing '4' in terms of the power of 2, we get:}\\\\\\\implies 2^{(x+5)} = 2^{2(x-1)}\\\\\\\text{Since the bases are same, we equate the powers. Hence,}\\\\\\\implies (x + 5) = 2 ( x - 1 )\\\\\\\implies ( x + 5 ) = 2x - 2 \\\\\\\implies 5 + 2 = 2x - x\\\\\\\implies \boxed{ \bf{ x = 7} }$

Hence the required value of 'x' is 7.

Answer 2

(2-5x) (7x² -3)

= 2(7x² - 3) - 5x(7x² - 3)

= 14x² - 6 - 35x³ - 15x