Question

factorise x^2-2x-80​

Answer 1

Answer: 1.1     Factoring  x2+2x-80

The first term is,  x2  its coefficient is  1 .

The middle term is,  +2x  its coefficient is  2 .

The last term, "the constant", is  -80

Step-1 : Multiply the coefficient of the first term by the constant   1 • -80 = -80

Step-2 : Find two factors of  -80  whose sum equals the coefficient of the middle term, which is   2 .

     -80    +    1    =    -79

     -40    +    2    =    -38

     -20    +    4    =    -16

     -16    +    5    =    -11

     -10    +    8    =    -2

     -8    +    10    =    2    That's it

Step-3 : Rewrite the polynomial splitting the middle term using the two factors found in step 2 above,  -8  and  10

                    x2 - 8x + 10x - 80

Step-4 : Add up the first 2 terms, pulling out like factors :

                   x • (x-8)

             Add up the last 2 terms, pulling out common factors :

                   10 • (x-8)

Step-5 : Add up the four terms of step 4 :

                   (x+10)  •  (x-8)

            Which is the desired factorization

Step-by-step explanation:

Answer 2

(x-10)(x+8) is the answer