Question 1121353: what two numbers added equal -7 and multiplied equal -8 Found 3 solutions by ikleyn, math_helper, MathTherapy:Answer by ikleyn(52786) (Show Source):
The standard solution is THIS:
x + y = -7 (1)
xy = -8 (2)
From eq(1) express y = -7-x and substitute it into eq(2). You will get
x*(-7-x) = 8
x*(7+x) = 8
x^2 + 7x - 8 = 0
= = .
Answer. The numbers are = 1 and = -8.
You can put this solution on YOUR website! what two numbers added equal -7 and multiplied equal -8
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Let x and y be the two numbers
x+y = -7 —> x = -7-y
xy = -8
Re-write the bottom equation with -7-y substituted for 'x':
(-7-y)y = -8
y=-8 ==> x=1
y=1 ==> x=-8
These are the same answer, as they just swap x and y in a trivial manner.
So the answer is and
FACTORS of 8:
Of these 2 sets of factors, only 8 and 1 can give a SUM or DIFFERENCE of 7, so the 2 factors, 8 and 1 are the 2 factors that are needed.
Now, we just have to place the signs!
Since when they're added and multiplied, they result in - 7 and - 8, respectively, it goes without saying that the 2 factors are:
