Experience the power of community-driven knowledge on IDNLearn.com. Our platform provides accurate, detailed responses to help you navigate any topic with ease.

activity 8.counting the roots of polynomial equation

by inspection determine the number of real roots of each polynomial equation. Roots multiply n are counted n times

1.(x-4)(x+3)^2(x-1)^3=0
2.x^2(x^3-1)=0
3.x(x+3)(x-6)^2=0
4.3x(x^3-1)^2=0
5.(x^3-8)(x^4+1)=0​

patulong po plss.

....


Sagot :

Answer and Step-by-step explanation:

A root is considered a real root if it is not an imaginary number (a number in the form of a + bi, where i is a number that is not on the real number line, hence the name: imaginary). Let's inspect the given polynomials.

1. (x-4)(x+3)^2(x-1)^3=0, the equation implies

x – 4 = 0 or (x + 3)^2 = 0 or (x – 1)^3 = 0, this gives:

x = 4

x = –3 twice

x = 1 thrice

They are all real numbers, therefore it has 6 real roots.

2. x^2(x^3-1)=0

x² = 0

x³ – 1 = x³ – 1³ = (x – 1)(x² + x + 1) = 0

The quadratic expressions gives 2 imaginary roots. To check this we can use the determinant formula.

D = b² – 4ac = 1² – 4(1)(1) = 1 – 4 = –3 < 0. This gives roots that are not real.

Therefore the real roots of this polynomial are: 0(twice) and 1. Hence, it has 3 real roots.

3. x(x+3)(x-6)^2=0

x = 0

x = 3

x = 6 twice

Thus, it has 4 real roots.

4. 3x(x^3-1)^2=0

3x = 0 and this gives x = 0

(x^3 – 1)² = [(x – 1)(x² + x + 1)]² = (x – 1)²(x² + x + 1)² = 0, only two roots are real here (the quadratic expression has unreal roots, therefore 1 twice are the real roots).

Therefore, this has 3 real roots.

5. (x^3-8)(x^4+1)=0

x³ – 8 = x³ – 2³ = (x – 2)(x² + 2x + 4) = 0

The only real root here is 2, the quadratic expression had imaginary roots and can be checked using the determinant formula

D = b² – 4ac = 2² – 4(1)(4) = 4 – 16 = – 12 < 0.

x⁴ + 1 = 0 has imaginary roots. Therefore, this polynomial has only one real root.