Factor the trinomial -x^2 - 3x + 28, if the lead coefficient is negative, I begin factoring out -1, then I think the answer is (x + 7)( x-4) please help me
2007-05-26 04:32:31 · 5 answers · asked by delphiniums 1 in Science & Mathematics ➔ Mathematics
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2007-05-26 04:35:44 · answer #1 · answered by Anonymous · 0⤊ 1⤋
First: the leading variable has to be positive > factor out a negative sign.
-(x^2 + 3x - 28)
Sec: factor > multiply the 1st & 3rd term to get (-28). find two numbers that give you (-28) when multiplied & 3 (2nd term) when added/subtracted. the numbers are (7 & - 4). rewrite the expression with the new middle terms.
x^2 + 7x - 4x - 28
Third: with 4 terms - group "like" terms & factor both sets of parenthesis.
(x^2 + 7x) - (4x - 28)
x(x + 7) - 4(x + 7)
(x + 7)(x - 4)
Now, combine the negative sign (that was factored earlier) with the parenthesis.
-(x + 7)(x - 4)
2007-05-26 05:09:07 · answer #2 · answered by ♪♥Annie♥♪ 6 · 0⤊ 0⤋
= - (x² + 3x - 28)
= - (x + 7).(x - 4)
= (x + 7).(4 - x)
2007-05-27 07:04:55 · answer #3 · answered by Como 7 · 0⤊ 0⤋
YOu have it correct
2007-05-26 04:35:18 · answer #4 · answered by txmama423 3 · 0⤊ 1⤋
that would be correct ........ good luck with rest
2007-05-26 04:40:25 · answer #5 · answered by Anonymous · 0⤊ 1⤋