How do you factor $x^2 + 3x -5x^2 - 15$ ?

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Answer 1 · 2015-05-19T05:10:52

Please check the question?

$y = -4x^2 + 3x - 15.$

This trinomial can't be factored because D = b^2 - 4ac < 0.

The correct question should be: factor $y = x^3 + 3x - 5x^2 - 15.$
To factor, group the first term and the second term together:

$y = x(x^2 + 3) - 5(x^2 + 3) = (x^2 + 3)(x - 5)$

Check by developing: $y = x^3 - 5x^2 + 3x - 15.$ OK

How do you factor x^2 + 3x -5x^2 - 15x^2 + 3x -5x^2 - 15?