Question

关于方程3^x＋x^2＋2x－1＝0,为什么方程有一负实根,一零根?..

Answer 1

3^x+(x^2+2x-1)=0;

3^x+(x+1)^2-2=0;

3^x+(x+1)^2=2;

3^x=2-(x+1)^2;

(x+1)^2>=0;

3^x