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how to factor 5s2 +19s -4? (step by step)

 Oct 14, 2015

Best Answer 

 #2
avatar+109812 
+5

how to factor 5s^2 +19s -4?

 

You need to find 2 numbers that multiply to 5*-4=-20   (so one is neg and one is pos)

 

and add to +19        (so the 'big' one is positive)

 

they would be +20 and -1

 

split   19s up into  20s-1s

 

\(5s^2+19s-4\\ =5s^2+20s-1s-4\\ \mbox{factorise in pairs}\\ =5s(s+4)-1(s+4)\\ =(5s-1)(s+4)\)

 

That is as far as you can go :))

 Oct 15, 2015
 #1
avatar+94 
+3

5s+  19s -4

(5s -1)(s +4)

s= { 1/5 , -4 }

 Oct 14, 2015
 #2
avatar+109812 
+5
Best Answer

how to factor 5s^2 +19s -4?

 

You need to find 2 numbers that multiply to 5*-4=-20   (so one is neg and one is pos)

 

and add to +19        (so the 'big' one is positive)

 

they would be +20 and -1

 

split   19s up into  20s-1s

 

\(5s^2+19s-4\\ =5s^2+20s-1s-4\\ \mbox{factorise in pairs}\\ =5s(s+4)-1(s+4)\\ =(5s-1)(s+4)\)

 

That is as far as you can go :))

Melody Oct 15, 2015

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