Question

If 8 ∙ 2x = 5(y+8), then when y = -8, x = 

(a) -4, (b) -3, (c) 0, (d) 4, (e) 8​

Answer 1

Solution:

8 ∙ 2x = 5(y+8).

or, 8 ∙ 2x = 5(-8+8).

or, 2x = 50.

or, 2x = 1 [anything to the power 0 is 1 then, 50 = 1].

Taking log on both sides,

log 2x = log 1.

or, x log 2 = 0 [since log 1 = 0].

or, x = 0/log 2 [dividing log 2 on both sides].

Therefore, x = 0.

Answer: (c)