Log3(x2+2x-2×2/3)=-1 How?

1 Answer
May 15, 2018

x_1=-(3+2sqrt6)/3
x_2=(-3+2sqrt6)/3

Explanation:

Log_3(x²+2x-4/3)=-1
D_f:x²+2x-4/3>0
D_f:x in ]-oo;-(3+sqrt21)/3[U] ((-3+sqrt21)/3);+oo[
Now :
ln(x²+2x-4/3)/ln3=-1
ln(x²+2x-4/3)=-1*ln3
Because alnb=lnb^a,
ln(x²+2x-4/3)=ln(1/3)
x²+2x-4/3=1/3
x²+2x-5/3=0
Δ=2²-4*1*(-5/3)
Δ=4+20/3
Δ=32/3
So: x_1=-(2+sqrt(32/3))/2
x_2=(-2+sqrt(32/3))/2
x_1=-(3+2sqrt6)/3
x_2=(-3+2sqrt6)/3
\0/ here's our answer!