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Look for numbers that multiply to be 14, and add(or subtract) to be 5). In this case you want subtraction, since the x2 is negative. If you cannot figure out the factors, use the quadratic formula:

For ax2 + bx + c:

[-b +/- sqrt(b2 -4ac)] / (2a) = [-5 +/- sqrt(52 -4*(-1)*14)] / (-2) = 5/2 +/- sqrt(81)/2

= 5/2 +/- 9/2 --> 14/2 & -4/2 --> 7 & -2.

so this would factor to (-1)*(x - 7)*(x + 2) = (-x + 7)*(x + 2)

Note that 7*2=14 and 7x - 2x = 5x.

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14y ago

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