+0  
 
0
143
2
avatar+2615 

The expression \(x^2 + 3x - 28\) can be written as \((x + a)(x - b),\) and the expression \(x^2 - 10x - 56\) written as \((x + 2b)(x + c)\), where \(a\)\(b\), and \(c\) are integers such that \(c > 0.\) What is the value of \(2c-a\)?

tertre  Dec 29, 2017
edited by tertre  Dec 29, 2017
Sort: 

2+0 Answers

 #1
avatar+502 
0

I wish I could help u guys but I forgot how to solve these type of questions cuz I used to solve them in grade 9 and 10

Rauhan  Dec 29, 2017
 #2
avatar+7056 
+1

x2 + 3x - 28   =   (x - 4)(x + 7)   =  ( x + (-4) )( x - (-7) )   =   (x + a)(x - b)

 

x2 - 10x - 56   =   (x - 14)(x + 4)   =   ( x + 2(-7) )( x + 4 )   =   (x + 2b)(x + c)

 

So...

a  =  -4  ,   b  =  -7  ,   c  =  4

 

And...

2c - a   =   2(4) - -4   =   8 - -4   =   12

hectictar  Dec 29, 2017

12 Online Users

avatar

New Privacy Policy (May 2018)

We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive pseudonymised information about your use of our website. Please click on "Accept cookies" if you agree to the setting of cookies. Cookies that do not require consent remain unaffected by this, see cookie policy and privacy policy.