+0  
 
0
84
2
avatar

 Given that a and b are positive integers and that a + b = 24 , what is the value of ab if 2ab + 10a  = 3b + 257 ?

 Nov 26, 2020
 #1
avatar+40 
+3

 a + b  =  24      so    b = 24 - a

 

Sub this into the other equation

 

2a (24 - a)  + 10a  = 3(24 - a) + 257 

 

48a - 2a^2  + 10a  = 72 - 3a  + 257

 

-2a^2 + 58a   = 329 - 3a 

 

2a^2 - 61a + 329  = 0 

 

(2a - 47)(a - 7)  =  0

 

only one of the solutions for a is an integer and it is 7

 

7 + b = 24

 

b = 17

 

(7)(17)=119

 Nov 26, 2020
 #2
avatar+116126 
0

Very nice, ChattyChen  !!!!

 

cool cool cool

CPhill  Nov 26, 2020

75 Online Users

avatar