JAMB - Mathematics (2011 - No. 6)
If log318 + log33 - log3x = 3, Find x.
1
2
o
3
คำอธิบาย
log\(_{3}^{18}\) + log\(_{3}^{3}\) - log\(_{3}^{x}\) = 3
log\(_{3}^{18}\) + log\(_{3}^{3}\) - log\(_{3}^{x}\) = 3log33
log\(_{3}^{18}\) + log\(_{3}^{3}\) - log\(_{3}^{x}\) = log333
log3(\(\frac{18 \times 3}{X}\)) = log333
\(\frac{18 \times 3}{X}\) = 33
18 x 3 = 27 x X
x = \(\frac{18 \times 3}{27}\)
= 2
log\(_{3}^{18}\) + log\(_{3}^{3}\) - log\(_{3}^{x}\) = 3log33
log\(_{3}^{18}\) + log\(_{3}^{3}\) - log\(_{3}^{x}\) = log333
log3(\(\frac{18 \times 3}{X}\)) = log333
\(\frac{18 \times 3}{X}\) = 33
18 x 3 = 27 x X
x = \(\frac{18 \times 3}{27}\)
= 2