Stanford University Exponential Problem. Admission Test .✍️🖋️📘💙

[@赖皮球]

3^x=t 0=t^2-16t-4 =(t-8)^2-68 t=sqrt(68)+8

[@prollysine]

3^(x+y)=3^(log4/log3) , x+y=log4/log3 , x=log4/log3 - y , 3^(log4/log3 - y)-3^y=16 , 3^(log4/log3)/3^y-3^y=16 , 3^(2y)+16*3^y-3^(log4/log3) ,
let u=3^y , u^2+16u-3^(log4/log3) , u= 2*(V17-4) , /-2(V17+4) < 0 /, y=log(2*(V17-4))/log3 , y=~ -1.27576 ,
x=log4/log3 - y , x=~2.53762 test , 3^(x+y)=4 , OK , 3^x-3^y=16 , OK ,