Question

usado apenas que log 20 = 1,30, log 30 = 1,47 , e log 60 = 1,79 , calcule :
log 16 + 2 log 5 =
2 log 15 + log 4 =
log 225 + 2 log 4 =
log 20 + log 45 =

Answer 1

$log16+2log5= \\ log16+log5^{2}= \\ log16+log25= \\ log(16.25)= \\ log400= \\ log20^{2}= \\ 2log20= \\ 2.1,30=2,60$

$2log15+log4= \\ log15^{2}+log4= \\ log225+log4= \\ log(225.4)= \\ log900= \\ log30^{2}= \\ 2log30= \\ 2.1,47=2,94$

$log225+2log4= \\ log15^{2}+2log4= \\ 2log15+2log4= \\ 2log(15.4)= \\ 2log60= \\ 2.1,79=3,58$

$log20+log45= \\ log(20.45)= \\ log900= \\ log30^{2}= \\ 2log30= \\ 2.1,47=2,94$

Answer 2

$log16+2.log5=log16+log5^{2}=log16+log25=log16.25=log400=\\log20^{2}=2.log20=2.1,30=2,60\\\\2.log15+log4=2.log\frac{30}{2}+log4=log(\frac{30}{2})^{2}+log4=\\log\frac{900}{4}+log4=log900-log4+log4=\\log900=log30^{2}=2.log30=2.1,47=2,94\\\\log225+2log4=log225+log4^{2}=log225+log16=log225.16=\\log3600=log60^{2}=2log60=2.1,79=3,58\\\\log20+log45=log20+log(\frac{30.30}{20})=log20+log30+log30-log20=\\2log30=2.1,47=2,94$

O Mozean espera ter ajudado!