MR-334 / 334. zadatak

Rešite donju jednačinu:

log10x2+19-log10x-8=2

log10x2+19-log10x-8=2
log10x2+19-log10x-8=2
log10x2+19-log10x-8=log10102
log10x2+19-log10x-8=log10100
log10x2+19x-8=log10100
x2+19x-8=100
x2+19=100x-8
x2+19=100x-800
x2+19-100x+800=0
x2-100x+819=0
x1,2=100-10000-32762
x1,2=100±67242
x1,2=100±822
x1=91 x2=9