Question

show that 5 is a zero of polynomial 2x^3-7x^2-16x+5

Answer 1

2x³ - 7x² - 16x + 5
when x = 5,

2(5³) - 7(5²) - 16(5) + 5
= 2(125) - 7(25) - 80 + 5
= 250 - 175 - 75
= 0

yes, 5 is the zero of the polynomial..

Answer 2

Given:

2x^3 - 7x^2 - 16x + 5.

To Find:

To show that 5 is a zero of the polynomial 2x^3 - 7x^2 - 16x + 5.

Solution:

If 5 is a zero of the polynomial 2x^3 - 7x^2 - 16x + 5 then,

x = 5.

So,

2*(5)^3 - 7*(5)^2 - 16*5 + 5 = 0.

2*125 - 7*25 - 16*5 + 5 = 0.

250 - 175 - 80 + 5 = 0.

75 - 80 + 5 = 0.

- 5 + 5 = 0.

0 = 0.

So, L.H.S. = R.H.S.

Hence, 5 is a zero of the polynomial 2x^3 - 7x^2 - 16x + 5.