Posted by kelli on Thursday, September 23, 2010 at 9:15pm.
Prove that there is a number that is exactly one more than its cube. (don’t solve just show there is one)
Prove that the function f(x)= cosxx has a zero in (o. pi/2) Justify.

calculus  Reiny, Thursday, September 23, 2010 at 10:15pm
x = x^3 + 1
x^3  x + 1 = 0
let f(x) = x^3  x + 1
every cubic function, just like every odd exponent equation, crosses the xaxis at least once.
BTW, how about x = appr. 1.3247
for cosx  x = 0
cosx = x
graph y = cosx an y = x on the same graph
they only cross once, hence one solution