Question

if-1 is a zero of the polynomial f(x) =x^2-7x-8 then calculate the other zero​

Answer 1

Answer:

x is equal to 8.

Step-by-step explanation:

if x=8 , x sqaure equal to 64, -7x =-56,and add of all is zero.

Answer 2

Answer :

• The other zero = 8

Step-by-step explanation :

➤ Quadratic Polynomials :

   ✯ It is a polynomial of degree 2

   ✯ General form :

             ax² + bx + c  = 0

             $\boxed{\bf x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}}$

                             

   ✯ Determinant, D = b² - 4ac

   ✯ Based on the value of Determinant, we can define the nature of roots.

           D > 0 ; real and unequal roots

           D = 0 ; real and equal roots

           D < 0 ; no real roots i.e., imaginary

   ✯ Relationship between zeroes and coefficients :

             ✩ Sum of zeroes = -b/a

             ✩ Product of zeroes = c/a

_________________________________

Given,

polynomial f(x) = x² - 7x - 8

It is of the form ax² + bx + c

 a = 1 , b = -7 , c = -8

⇒ one of the zeroes = -1

 let the other zero be "p"

we know,

 product of zeroes = constant term/x² coefficient

     (-1) × p = -8/1

       -p = -8

         p = 8

∴ The other zero = 8

Verification :

sum of zeroes = 8 + (-1)

                         = 8 - 1

                         = 7

                         = -(-7)/1

                         = -x coefficient/x² coefficient