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Mathematics 16 Online
OpenStudy (iwanttogotostanford):

PLEASE HELP< IM LOST: DETAILS BELOW ALGEBRA QUESTION PLZ HELP

OpenStudy (iwanttogotostanford):

@CoolDude12 @imqwerty @pooja195 @triciaal

OpenStudy (anonymous):

what grade are you in?

OpenStudy (iwanttogotostanford):

Sophomore

OpenStudy (anonymous):

what is that?

OpenStudy (iwanttogotostanford):

10th grade of high school

OpenStudy (anonymous):

oh

OpenStudy (anonymous):

sorry i cant help you im only in 6th grade

OpenStudy (iwanttogotostanford):

@YoungStudier @imqwerty please help

OpenStudy (iwanttogotostanford):

@phi

OpenStudy (phi):

It sounds like they gave you a list of expressions in column A and column B pick one of the expressions from column A what is it ?

OpenStudy (phi):

you should choose one from column A

OpenStudy (iwanttogotostanford):

ok so (x+y)

OpenStudy (phi):

now square it. that means multiply it by itself (x+y)(x+y) if you don't know how, this explains it: https://www.khanacademy.org/math/algebra-basics/quadratics-polynomials-topic/multiplying-binomials-core-algebra/v/multiplying-binomials

OpenStudy (iwanttogotostanford):

so I would get x^2+xy+yx+y^2? @phi

OpenStudy (phi):

yes, and yx is the same as xy (yx means y times x, and we can switch the order when multiplying) also xy+xy means we have 2 xy's and people would combine them to just 2xy so the answer is x^2 +2xy+y^2

OpenStudy (iwanttogotostanford):

i really need help with the whole process please if you could

OpenStudy (phi):

you could write it 2yx but generally people write the variables in alphabetical order (just a convention)

OpenStudy (phi):

they want you to add it to one factor from column B so pick an expression from column B

OpenStudy (iwanttogotostanford):

ok (ax+b)

OpenStudy (phi):

add it x^2 +2xy+y^2 + ax + b which can be written in this order x^2 +ax+ 2xy+y^2 + b

OpenStudy (iwanttogotostanford):

ok so how would i add those all together to make it coherent

OpenStudy (iwanttogotostanford):

is that it written already combined?

OpenStudy (phi):

you can't do anything more , unless we have numbers for a and b I am not sure what they want out of this exercise. what you have shown is (x+y)^2 + ax+b = x^2 +ax + 2xy + y^2 + b

OpenStudy (iwanttogotostanford):

ok so would my final answer just be : x^2 +ax+ 2xy+y^2 + b?

OpenStudy (phi):

yes

OpenStudy (phi):

can you make a photo or screen shot of the original problem ?

OpenStudy (phi):

What I am trying to figure out is if we can replace a and b with numbers. for example use (2x+3) (with a=2 and b=3) then your answer would be (x+y)^2 + 2x+3 = x^2 +2x + 2xy + y^2 + 3 now we can show this identity works for different x and y values for example, for (0,0) we get (0+0)^2 + 2*0 + 3 = 0^2 +2*0 +2*0*0 + 0^2 + 3 3 = 3 they want you to show that for a few (x,y) pairs of numbers.

OpenStudy (phi):

I think that is what Demonstrate that your polynomial identity works on numerical relationships is what that means

OpenStudy (phi):

For this part Prove that it is true through an algebraic proof, identifying each step write the starting expression (x+y)^2 + 2x+3 and show your work for squaring (x+y) and then adding 2x+3

OpenStudy (iwanttogotostanford):

ok! so what do I need to do to get my composite final answer as a whole??

OpenStudy (phi):

what do you mean?

OpenStudy (iwanttogotostanford):

what would I write as my final answer(s) for the project? How would I put together my answer for this project

OpenStudy (phi):

design an advertisement for a new polynomial identity you are supposed to make a flyer or advertisement selling your identity your identity is (x+y)^2 + 2x+3 = x^2 + 2x + 2xy + y^2 + 3 you should put in some lines that say it works: show the algebra to show the left side becomes the right side then put in some numbers for x and y and show both sides simplify to the same number.

OpenStudy (iwanttogotostanford):

and what algebraic proof can I use to show that it works???

OpenStudy (phi):

A long ago people sold "pet rocks" see https://en.wikipedia.org/wiki/Pet_Rock if you can sell a rock as a pet, you can sell anything. I guess you should think of the expression as valuable information, that people would buy if they thought it was true, and then explain how it is true.

OpenStudy (phi):

algebraic proof that would just be the algebra you used to multiply out (x+y)^2 and then add 2x+3 (which is not hard, you just "tack" those terms onto the the first part)

OpenStudy (iwanttogotostanford):

how exactly do I show that in a proof though?

OpenStudy (iwanttogotostanford):

im not sure how to show each step

OpenStudy (phi):

you could do this (x+y)^2 = (x+y)(x+y) reason: definition of exponent 2 (x+y)(x+y)= x(x+y) + y(x+y) reason: distributive law of multiplication over addition x(x+y) = x^2 + xy reason: same as above y(x+y) = yx+ y^2 reason: as above therefore (x+y)(x+y)= x^2 + xy+yx + y^2 reason: substitution yx= xy reason: commutative law of multiplication therefore x^2 + xy+yx + y^2 = x^2 + xy+xy + y^2 reason: substitution = x^2 +2xy + y^2 reason: addition of like terms and so (x+y)^2 = x^2 +2xy + y^2 reason: rules of algebra

OpenStudy (phi):

and finally (x+y)^2 +2x+3 = x^2 + 2x + 2xy+y^2 + 3 reason: addition of equal terms to both sides

OpenStudy (iwanttogotostanford):

so is this on algebraic proof: x^2 + xy+yx + y^2 = x^2 + xy+xy + y^2 reason: substitution = x^2 +2xy + y^2 reason: addition of like terms and so (x+y)^2 = x^2 +2xy + y^2 reason: rules of algebra

OpenStudy (phi):

yes, but you have to start with (x+y)^2

OpenStudy (phi):

you could say (x+y)(x+y)= x^2 + xy+yx+y^2 reason: multiplication of two binomials that is not really a law of arithmetic (like the commutative or distributive laws) but you probably can get away with it. In the other post I showed how we can use the distributive law to do the multiplication.

OpenStudy (iwanttogotostanford):

@phi

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