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Course: Class 7>Unit 11

Lesson 2: Polynomials word problems

Polynomial word problem: rectangle and circle area

Sal writes a binomial to express the difference between the area of a rectangle and the area of a circle. Created by Sal Khan and Monterey Institute for Technology and Education.

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• why do they call it a triominal?
• Polynomials" refer to mathematical expressions that contain multiple terms (poly = multiple, nomials = terms/numbers (roughly)). "Monomial" refers to a polynomial that has only a single (mono) term.
• is there something bigger than trinominal?
• Well, a polynomial can have more than three terms, but there are no more specific terms - after three terms, it's just a polynomial.
• What is the equation of the area of a cirle
• pi * (r^2), where "r" is the radius of the circle and "pi" is, well, 3.14159265358979323846...
• how doe polynomials help in actual real life?
• Polynomials are like an express way of calculating financial planning, construction of materials, expense budgeting, and helps greatly in science. (finding initial velocities, gravitational acceleration, etc.)

http://www.ehow.com/info_10070112_polynomials-used-daily-life.html
• What is the largest number of real roots that a fourth degree polynomial could have? What is the smallest number?
• it could potentially have 4 real roots, in some cases it can have none. this is because there must be four solutions, real or imaginary. they may be all real or all imaginary as the exponent is even so it comes from a high positive to a high positive (imagine the graph) hope this helps
• At , Sal's final expression (2rp - 4πr^2) had three terms : r, p, and r^2. But didn't the question ask for a binomial, which has two terms? I'm confused....
• This expression has two terms. I think you counted the types of variables in the expression instead of the terms.

A term is an expression that doesn't have the operations of addition and subtraction.
2rp<---One term
4πr^2<---Second term
There are two terms in this expression; therefore, it's a binomial. I hope this helped!
• Ok I'm 17 in the 11th grade and new to khan and I'm seriously bad at math...like SERIOUSLY BAD! when I look at math equations all I see is a bunch of letters and numbers. I have a really hard time remembering what I learn too. :/ it's like I learn it then when I have to do it again the next day I have to re-learn everything. I'm pretty visual. Is there like a special way to maybe get a video chat thing with one of khan academy's teachers so they could like tutor me kinda if I need help?
• How do you find the degree of a polynomial