how do you multiply 2 polynomial terms in math grade 8 according to RS Aggarwal ?

Hello Yashashvi, multiplication of two polynomials can look tough but certainly they aren't. You have to multiply one factor of one term with all the factors at the other term and do it again till all factors in that term have been multiplied. Let us see how it works in an example since it is very confusing to understand in a theoretical manner:
Multiply: (3x+ y2) with (2x-3)
​Solution: ​(3x+ y2) x ​(2x-3)
              =6x3- 9x2 + 2xy2 - 3y2
And that's it! It was pretty simple to try out, but let's see another example:
Multiply: (5x2 - 6x + 9) with (2x2 - 5x + 4)
Solution: ​(5x2 - 6x + 9) x ​(2x2 - 5x + 4)
              =10x4 - 25x3 + 20x2 - 12x3 + 30x2 - 24x + 18x2 - 45x + 36
              =​10x- 25x3 ​- 12x3 ​+ 20x2 ​+ 30x2 ​+ 18x2 ​- 24x ​- 45x ​+ 36 
              =10x4 - 37x3 + 68x- 36x + 36
And that's it! So this is how we have to solve multiplication of Dual (Two) Polynomials according to RS Aggarwal: First multiply a factor with all the factors of another term, then do it repeatedly until you have finished multiplying all factors, then regroup like factors and solve the operations involved. I hope you understand it, to understand it more clearly try solving some problems related to this concept on your own on Meritnation or other websites!

Thank you!

            

  • 3
Hi,

It is a very easy concepts, which may look little complex, but, is done by some minor properties like Distributive property, commutative property . 

Multiplication of two polynomials.

Rule:
Multiply each term of  one polynomial by each term of another polynomial and then add the like terms.

Example 1:
Q.Product  of (2a + 3b) and  (3a + 4b)​
(2a + 3b) x (3a + 4b)
= 2a (3a+4b) + 3b (3a+4b)
= 6a2 + 8ab + 9ab + 12b2
= 6a2 + 17ab + 12b2


Example 2:
Q. Product of (x-2y) and  (x2 + 6xy – y2)

(x-2y) x (x2 + 6xy – y2)
= x(x2 + 6xy – y2) – 2y(x2 + 6xy – y2)
= x3 + 6x2y – xy2 – 2yx2 – 12xy2 +2y3
= x3 + 6x2y + (– xy2)+( – 2yx2) + (-12xy2)  +2y3
= x3 +{6x2y +( – 2yx2)} + {(– xy2) + (-12xy2)}  +2y3

= x3 + 4x2y – 13xy2 + 2y3

There can  be many such examples. 

Regards.


@ Shreyas: Good Effort. Keep answering!
  • 2
I was really glad to get my concepts clear and it was really very hepful, therefore thanks a lot shreyas and santanu for the great help in concept clearing....it was the first time i got help fom merination and the resuts looked fabulous...thank you 
Best Regards
 
  • 1
What are you looking for?