Question

2x^3+8x-7 how is this answer

Answer 1

It has 1 real root

Step-by-step explanation:

Given polynomial,

Since, the polynomial is arranged in descending powers of the variable and coefficients of our variable in f(x),

2, 0, 8, -7

Variables goes from positive(2) to 0 to positive(8) to negative(-7),

i.e. number of change in sign = 1,

Thus, there is only one positive real root,

Now,

Variables goes from negative(2) to 0 to negative(-8) to negative(-7),

i.e number of change in sign = 0,

Thus there is no negative real root.

∵ Degree of the polynomial = 3,

Hence, By Descartes's rule of sign,

The polynomial has 1 real roots and 2 imaginary root.