Sunday

February 1, 2015

February 1, 2015

Posted by **kelli** on Thursday, September 23, 2010 at 9:15pm.

Prove that the function f(x)= cosx-x has a zero in (o. pi/2) Justify.

- calculus -
**Reiny**, Thursday, September 23, 2010 at 10:15pmx = 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 x-axis 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

**Answer this Question**

**Related Questions**

calculus - prove that 5x - 7 - sin3x = 0 has at least one zero and prove that it...

Trignometry - Can you please help me prove that ((1-cosx)/(1+cosx))=(cscx-cotx)^...

Pre-calc - prove the identity: (cosx)(tanx + sinx cotx)=sinx+cos(squared)x i ...

Precalculus/Trig - Prove the following identity: 1/tanx + tanx = 1/sinxcosx I ...

Maths - Please help with these questions: (please show how to do) 1. How many ...

Pre-Calc - Trigonometric Identities Prove: (tanx + secx -1)/(tanx - secx + 1)= ...

math - Let f:ℤ+ → ℤ+ be the function defined by: for each x &#...

math help please - Let f:ℤ+ → ℤ+ be the function defined by: ...

discrete math - Let f:ℤ+ → ℤ+ be the function defined by: for...

ordered fields - prove (3x^2 + 4x-1)/(7x^5+5)>0 is field. can you just prove ...