SOLUTION: Q1 (i) Factor the expression 4y^2-12xy-8yz+9x^2+12xz+4z^2 (ii) Expand the expression(3x-2y+3z)^3/(5x-2y+z)^2 (iii)

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons -> SOLUTION: Q1 (i) Factor the expression 4y^2-12xy-8yz+9x^2+12xz+4z^2 (ii) Expand the expression(3x-2y+3z)^3/(5x-2y+z)^2 (iii)       Log On


   



Question 83397: Q1 (i) Factor the expression
4y^2-12xy-8yz+9x^2+12xz+4z^2
(ii) Expand the expression(3x-2y+3z)^3/(5x-2y+z)^2
(iii) Solve the equation:
x^5 – 2x^4 + x^3 – 2x^2 – 2x + 4 = 0

Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!

Here are the 1st and 3rd.
I haven't figured out the 2nd one yet.  
Is that the way it was given?  No errors?
Is it supposed to be a division?
You were asked to "expand a quotient"?  
That doesn't seem right.

Anyway here are the first and third ones:

Q1 (i) Factor the expression                          

4y%5E2-12xy-8yz%2B9x%5E2%2B12xz%2B4z%5E2                              

Rearrange the terms as

9x%5E2-12xy%2B4y%5E2 + 12xz+-+8yz + 4z%5E2

The first three terms factor as %283x-2y%29%283x-2y%29 or %283-2x%29%5E2

We can take 4z out of the 
3rd and 4th terms and we now have

%283x-2y%29%5E2+%2B+4z%283x-2y%29+%2B+4z%B2

Now let w+=+%283x-2y%29

Then the above becomes

w%5E2+%2B4zw+%2B+4z%5E2

which factors as

%28w+%2B+2z%29%28w%2B2z%29 or

%28w+%2B+2z%29%5E2

Now replace the w by (3x-2y)

%283x-2y%2B2z%29%5E2

----------------------------------

(iii) Solve the equation:
      
x%5E5-2x%5E4%2Bx%5E3-+2x%5E2+-+2x+%2B+4+=+0 

We notice that the coefficients of the
1st, 3rd, and 5th terms are 1,1,-2, and that
the coefficients of the 2nd, 4th, and 6th
terms are -2,-2,4 and that these are
proportional, so we rearrange the terms:

x%5E5%2Bx%5E3-2x-2x%5E2-2x%2B4=0

Factor x out of the first 3 terms and -2
out of the last 3 terms:

x%28x%5E4%2Bx%5E2-2%29-2%28x%5E4%2Bx%5E2-2%29=0 

Now we can take out the common factor 
%28x%5E4%2Bx%5E2-2%29 and we have:

%28x%5E4%2Bx%5E2-2%29%28x-2%29=0

Now we can factor the first parenthetical 
expression:

%28x%5E2%2B2%29%28x%5E2-1%29%28x-2%29=0

and finally factor the expression in 
the middle parentheses as the difference 
of two squares:

%28x%5E2%2B2%29%28x-1%29%28x%2B1%29%28x-2%29=0

Now we set each factor = 0:

Setting first factor = 0

x%5E2%2B2=0
x%5E2=-2

Use the principle of square roots  

    x = ±sqrt%28-2%29
    x = ±i%2Asqrt%282%29

Setting second factor = 0
    x - 1 = 0 gives x = 1

Setting third factor = 0
    x + 1 = 0 gives x = -1

Setting fourth factor = 0
    x - 2 = 0 gives x = 2

So the 5 solutions are ±isqrt%282%29,1,-1, and 2  

Edwin