If two polynomial equations have real solutions, then will the equation that is the result of adding, subtracting, or multiplying the two polynomial equations also have real solutions?

Respuesta :

No, there are polynomials that have real solutions but when combined would be possible to have no real solutions.

Answer:

No.

Step-by-step explanation:

No, one easy way to see it is with quadratic formulas. There exists quadratic polynomials with no real solutions, then if you add, subtract or multiply two polynomials and obtain a quadratic formula, possibly this polynomial won't have real solutions.

I am going to give one counterexample:

We have the two polynomials [tex]p(x) = x^2+2x+3[/tex] and [tex]q(x)= 2x^2+3x+4[/tex], then is we subtract q(x)-p(x) we obtain

[tex]2x^2+3x+4-(x^2+2x+3) = 2x^2+3x+4-x^2-2x-3 = x^2+x+1.[/tex]

The resulting polynomial is a quadratic polynomial of the form [tex]ax^2+bx+c[/tex] with a=1, b=1 and c=1. This polynomial has no real solutions, you can check it with the discriminating [tex]b^2-4ac = 1^2-4(1)(1) = 1-4 = -3.[/tex] As the discriminating is negative, the polynomial has no real solutions.

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