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How would you do 7x squared + 27xy + 18y squared? I'm so used to the format of x squared + x + ___(insert number here)

Anima  Feb 3, 2015

Best Answer 

 #1
avatar+91517 
+5

 I  expect you want me to factorize it?

 

$$\\7x^2+ 27xy + 18y^2\\$$

 

This is a tough one.  

We want to find 2 numbers that mult to 7*18  and add to 27

prime factors of 7*18  are  7*3*3*2   I notice straight off that 21+6=27

so the numbers are  21 and 6

change 27xy into    21xy+6xy

 

$$\\7x^2+ 27xy + 18y^2\\
=7x^2+ 21xy +6xy+ 18y^2\\
=7x(x+3y)+6y(x+3y)\\
=(7x+6y)(x+3y)$$

 

Do you understand Anima ?

Melody  Feb 3, 2015
Sort: 

1+0 Answers

 #1
avatar+91517 
+5
Best Answer

 I  expect you want me to factorize it?

 

$$\\7x^2+ 27xy + 18y^2\\$$

 

This is a tough one.  

We want to find 2 numbers that mult to 7*18  and add to 27

prime factors of 7*18  are  7*3*3*2   I notice straight off that 21+6=27

so the numbers are  21 and 6

change 27xy into    21xy+6xy

 

$$\\7x^2+ 27xy + 18y^2\\
=7x^2+ 21xy +6xy+ 18y^2\\
=7x(x+3y)+6y(x+3y)\\
=(7x+6y)(x+3y)$$

 

Do you understand Anima ?

Melody  Feb 3, 2015

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