Homework Help: algebra

Posted by Trina on Friday, September 3, 2010 at 5:54pm.

Use the discriminant to find out whether this quadratic polynomial can be factored. Factor the polynomial if it is not prime. This polnomial is prime, so I cannot factor it. I just need help with the discriminant part. Thaks in advance for your help.

4x^2-27x+45

algebra - drwls, Friday, September 3, 2010 at 6:06pm
The discriminant is b^2 - 4 ac = 729 -720 = 9. Since the square root of that is an integer (3), the polynomial can be factored.

The roots are (1/8)[27 +/-3] = 30/8 and 3

4x^2-27x+45 = (x-3)(4x- 15) are the factors

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