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a times b equals -8. a plus b equals 7. what is a and b?

 Aug 24, 2015

Best Answer 

 #2
avatar+26396 
+8

a times b equals -8. a plus b equals 7. what is a and b?

(1)ab=8(2)a+b=7b=7a(2) in (1)a(7a)=87aa2=8a27a8=0(a8)(a+1)=0a1=8a2=1b1=7a1b1=78b1=1b2=7a2b2=7(1)b2=7+1b2=8

 

a1=8 and b1=1a2=1 and b2=8

 Aug 24, 2015
 #1
avatar+15054 
+5

Hallo anonymous!

 

a times b equals -8. a plus b equals 7. what is a and b?

 

a * b = - 8

a + b = 7

a = - 8 / b

a = 7 - b

- 8 / b = 7 - b

- 8 = 7b - b²

b² - 7- 8 = 0

b1;2 = - (p/2) ±√((p/2)² -q)

b1;2 = 3,5 ±√ (3,5² + 8)

b1;2 = 3,5 ±√ 20,25 = 3,5 ± 4,5

b1 = 8

b2 = -1

 

a1;2 = 7 - b

a1 = -1

a2 = 8

 

test :

a1 * b1 = - 8                 

-1 * 8  = - 8   okey

a1 + b1 = 7

-1 + 8 = 7      okey

 

a2 * b2 = - 8

8 * (- 1) = - 8 okey

a2 + b2 = 7

8 + (-1) = 7 okey

 

greetings   :- )

 Aug 24, 2015
 #2
avatar+26396 
+8
Best Answer

a times b equals -8. a plus b equals 7. what is a and b?

(1)ab=8(2)a+b=7b=7a(2) in (1)a(7a)=87aa2=8a27a8=0(a8)(a+1)=0a1=8a2=1b1=7a1b1=78b1=1b2=7a2b2=7(1)b2=7+1b2=8

 

a1=8 and b1=1a2=1 and b2=8

heureka Aug 24, 2015

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