Question

0.00000042=4.2 10^x then x = ?

Answer 1

Answer:

if log (x) = -6.37, then how is x=4.2 × 10^-7?

Assuming the log is in base 10 — typical in the U.S., and also necessary to reach the above solution in this problem — then the following two statements are equivalent, by definition:

log10x=−6.37

x=10−6.37

Evaluating the latter yields

x=0.000000426579519

x≈4.3×10−7

To verify the answer, evaluating log10(4.3×10−7) yields approximately -6.37, as in the question.

Answer 2

$\huge\sf{Answer}$

$\sf{0.00000042\:=\:4.2\times \ 10^{-7}}$

$\sf{ \underline{ \underline{So,\:value\:of\:x\:is\:-7}}}$