One number is 9 more than another number. If the product of the two numbers is -20, find both numbers

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Answer 1

One way to solve quickly is to use the factors of -20 to solve your answer:

 

-20 * 1  (difference between the two is 21) as well as -1* 20

-10 * 2 (difference is 12) as well as -2* 10

-5 * 4  (difference is 9) as well as -4 *5

 

The answers are -4,5 and -5,4

 

 

or

 

(x) * (x+9) = -20

 

x²  + 9x =  -20

 

x² + 9x + 20 = 0

 

(X+4)(x+5) = 0

 

x= -4, -5         therefore  (-4 * 5 as well as -5 * 4)