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avatar+279 

The expression below is a sum of cubes.

 

64x^3 + 125

 

A. True

B. False

 

So far i have the entire cube written out as its shown below

 

(4x + 5) ( 4x^2 + ?x + 25)

 

So... ill like to know what do i do to get the middle part of the cube and to know if what i even did is correct...

 Oct 3, 2019
edited by CreatorRozen  Oct 3, 2019
 #1
avatar+19832 
+3

Sum of cubes ....true   (the cubes are 4x  and 5)

Her ya go

 

 Oct 3, 2019
edited by ElectricPavlov  Oct 3, 2019
 #2
avatar+279 
+1

Ah, now i see...

 

Thanks EP

 

btw for the middle number AB in red im assuming you Multiply (A+B) to get the AB?

 

if not... then i might be a bit confused

 

cool surprise cool

CreatorRozen  Oct 3, 2019
edited by CreatorRozen  Oct 3, 2019
edited by CreatorRozen  Oct 3, 2019
 #3
avatar+279 
+1

Nope ok i understand now

CreatorRozen  Oct 3, 2019
 #4
avatar+8652 
+3

\(64x^3+125\)

\(=(4x)^3+5^3\)

 

\(a^3+b^3\\ =(a+b)(a^2-ab+b^2)\\ a=4x;\ b=5\)

 

\((4x)^3+5^3\\ =(4x+5)(16x^2-20x+25)\)

laugh  !

 Oct 3, 2019

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