MHB Evaluating $f(15)$ without a Calculator

  • Thread starter Thread starter anemone
  • Start date Start date
  • Tags Tags
    Calculator
AI Thread Summary
The discussion focuses on evaluating the polynomial function f(x) at x=15 without a calculator. Participants share methods for simplifying the expression, highlighting the structure of the polynomial and its coefficients. Techniques such as factoring and substitution are discussed to arrive at the value of f(15). The conversation emphasizes collaborative problem-solving and encourages engagement among participants. Ultimately, the evaluation of f(15) showcases the effectiveness of analytical approaches in polynomial calculations.
anemone
Gold Member
MHB
POTW Director
Messages
3,851
Reaction score
115
Let $f(x)= x^{11}-16x^{10}+16x^9-16x^8+16x^7-16x^6+16x^5-16x^4+16x^3-16x^2+16x-1$.

Evaluate $f(15)$ without using the calculator.
 
Mathematics news on Phys.org
anemone said:
Let $f(x)= x^{11}-16x^{10}+16x^9-16x^8+16x^7-16x^6+16x^5-16x^4+16x^3-16x^2+16x-1$.

Evaluate $f(15)$ without using the calculator.

we have

$f(x) = x^{10}(x-15) - x^9(x-15) + x^8(x-15) - x^7(x-15) + x^6(x-15) - x^5(x-15) + x^4(x-15) - x^3(x-15) + x^2(x-15) - x(x-15) + x - 1$

so f(15) = 14
 
kaliprasad said:
we have

$f(x) = x^{10}(x-15) - x^9(x-15) + x^8(x-15) - x^7(x-15) + x^6(x-15) - x^5(x-15) + x^4(x-15) - x^3(x-15) + x^2(x-15) - x(x-15) + x - 1$

so f(15) = 14

Very well done, kaliprasad, and thanks for participating!:)
 
By inspection, $$x-1$$ is a factor of $$f(x)$$. After polynomial long division, we have

$$f(x)=(x-1)(x^{10}-15x^9+x^8-15x^7+x^6-15x^5+x^4-15x^3+x^2-15x+1)$$

so

$$f(15)=14\cdot1=14$$
 
Last edited:
greg1313 said:
By inspection, $$x-1$$ is a factor of $$f(x)$$. After polynomial long division, we have

$$f(x)=(x-1)(x^{10}-15x^9+x^8-15x^7+x^6-15x^5+x^4-15x^3+x^2-15x+1)$$

so

$$f(15)=14\cdot1=14$$

Very good job, greg1313! And thanks for participating! :)
 
Suppose ,instead of the usual x,y coordinate system with an I basis vector along the x -axis and a corresponding j basis vector along the y-axis we instead have a different pair of basis vectors ,call them e and f along their respective axes. I have seen that this is an important subject in maths My question is what physical applications does such a model apply to? I am asking here because I have devoted quite a lot of time in the past to understanding convectors and the dual...
Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. In Dirac’s Principles of Quantum Mechanics published in 1930 he introduced a “convenient notation” he referred to as a “delta function” which he treated as a continuum analog to the discrete Kronecker delta. The Kronecker delta is simply the indexed components of the identity operator in matrix algebra Source: https://www.physicsforums.com/insights/what-exactly-is-diracs-delta-function/ by...

Similar threads

Back
Top