Question

How to solve polynomials

Answer 1

the price of LED TV is 48000 the shop is given 2% discount with using credit card or debit card how much cost of a TV

Answer 2

There are two methods:

1) Trial and Error:

In this one,  we just put random values of x so we can get a zero.

for example, we have 
p(x) = 2x² + x -1
Now, lets try to put the value of x as 1
p(1) = 2(1)² + (1) - 1
      = 2 + 1 - 1
      = 4
∴p(1) ≠ 0

Now let's try to put the value of x as -1
p(-1) = 2(-1)² + (-1) - 1
        = 2 - 1 -1
        = 0
∴ x = -1


2) Factorisation by splitting the middle term
We have a polynomial ax² + bx + c
We have to multiply a and c 
Now, the factors of ac are added or subtracted so that b is obtained.
It may sound confusing but here, take a look at an example.
Let us take the same polynomial we used earlier.

  2x² + x - 1
=2x² + 2x - x - 1                 (∵ (2)(-1) = (-2) and (-1)+2 = 1 )
= 2x(x+1) -1 (x+1)
= (2x-1)(x+1)
∵ 2x-1 = 0                   ∵x+1 = 0
   x = 1/2                        x = -1