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lions [1.4K]
3 years ago
11

PLease solve this factorize: x^2-4x-21+10y-y^2

Mathematics
2 answers:
natita [175]3 years ago
5 0

Answer:

(x - y + 3)(x + y - 7)

Step-by-step explanation:

x^2 - 4x - 21 + 10y - y^2

= x^2 - y^2 +10y - 4x - 21

= (x - y)(x + y) + 10y - 4x - 21

This is a stab in the dark - I think this might factor to (x - y + 3)(x + y - 7)  or

(x - y - 7)(x + y + 3) - I think I've come across one like this before.

Lets try the first one:

(x - y + 3)(x + y - 7) = x^2 + xy - 7x - y^2 - xy +3y + 3x + 7y - 21

= x^2 -7x + 3x -21 + 10y  - y^2.

This is correct but isn't a very logical way to do this. There must be a better way!

The logical way is  by reducing the expression to the difference of 2 squares: (x - 2)^2 - (y - 5)^2

This factors to ( x + y -7)(x - y + 3).

kompoz [17]3 years ago
4 0

 

\displaystyle\bf\\x^2-4x-21+10y-y^2=\\=x^2-y^2 -7x+3x+7y+3y -21=\\\\=(x-y)(x+y) -7x+7y +3x+3y-3\cdot7=\\\\=\boxed{\bf(x+y-7) (x-y+3)}

 

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Answer:

a: no solutions

b: (2, 3)

Step-by-step explanation:

a:

In both equations, the slope of x is the same, but the y-intercept is not, which means they are parallel. Therefore, this system of equations has no solutions.

b:

Since both of the equations are equal to y, we can set them equal to each other:

\frac{1}{2}x^2+1= 2x-1\\x^2 + 2 = 4x - 2\\x^2-4x+4=0

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(x-2)^2 = 0

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Now, to find y, plug-in x to any of the equations:

y = 2*2-1 = 3

Therefore, the solution to this system of equation is (2, 3)

I hope this helped.

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There's a strong negative association between the two variables.


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Answer:

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Step-by-step explanation:

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