2-var. induction Q: find n1 for (1+x)^n >1 +n*x + n*x^2

(1+x)^k * (1+x) > 1 + (k+1)*x + (k+1)*x^2 + (k-1)x^2+ kx^3

(1+x)^k * (1+x) > 1 + (k+1)*x + (k+1)*x^2

how did the (k-1)x^2+ kx^3 dissapeared?
 
transgalactic said:
(1+x)^k * (1+x) > 1 + (k+1)*x + (k+1)*x^2 + (k-1)x^2+ kx^3

(1+x)^k * (1+x) > 1 + (k+1)*x + (k+1)*x^2

how did the (k-1)x^2+ kx^3 dissapeared?

Think about it. What am I saying - while I made them disappear?
 
transgalactic said:
you proved more then you should have then you erase this positive members to fit
equation2

Correct - now what was your question (did you answer it yourself?)
 
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