Posted by Bethany on Wednesday, June 8, 2011 at 11:23pm.
lgt(a)+lgt(b)=lgt(a*b)
lgt(x+4)+lgt(x-4)=4
lgt[(x+4)*(x-4)]=4
lgt is the logarithm with base 10.
Antilogarithm of this expresion is
(x+4)*(x-4)=10^4
(x+4)*(x-4)=10.000
x^2+4x-4x-4*4=10.000
x^2-16=10.000
x^2=10.000+16
x^2=10.016
x=sqroot(10.016)
x=100.0799680256