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5 votes
What two numbers adds up to 7 but multiply to -8

User Tony Maro
by
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2 Answers

2 votes
Let, the numbers = a, b

Then, a + b = 7
& a * b = -8

Substitute the value of a from Equation (1) into (2),
(7-b) * b = -8
7b - b² = -8
b² - 7b - 8 = 0
b² + b - 8b - 8 = 0
b(b + 1) -8(b + 1) = 0
(b + 1)(b - 8) = 0
b = -1 OR 8

In short, Your Numbers would be: -1 & 8

Hope this helps!
User Suvtfopw
by
6.3k points
6 votes
ans is 8 and -1

8 + (-1) = 7

and

8 * (-1) = -8

User Sajanyamaha
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6.6k points