Solving systems equations by elimination

1 answer:

3 0

I won't answer them all for you (don't want to cheat - need to learn something).
But for the first one given:

<span>-2x-9y=-25
-4x-9y=-23

you set up either x or y (which ever one you want to eliminate) so that one of them cancels.
So this one is easy - you just have to multiply an entire row by negative (doesn't matter which one) - so that the y's will be + and -

Since they're both 9 and they're subracting NOW - you can eliminate the y value. Now add/subtract the x's. So it'd be -2 or 2 depending on how you eliminated y. Then add the number outside of the = sign. Now just solve for x. After that plug in whatever you got for x into both of the rows. Then find the y value.

Hopefully this wasn't confusing -- reply if it is and I will try to simplify. I can give you contact if you need help with the rest

Good luck!</span>

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Solve for x: 4 over x plus 4 over quantity x squared minus 9 equals 3 over quantity x minus 3

dezoksy [38]

Answer:

Step-by-step explanation:

4/x + 4/(x²-9) = 3/(x - 3)

4 / x + 4 / [( x - 3) ( x + 3 )] = 3 / ( x - 3 ) / * x ( x - 3 ) ( x + 3 )

Restrictions : x ≠ 0, x ≠ - 3 , x ≠ 3;

4 ( x + 3 ) ( x - 3 ) + 4 x = 3 x ( x + 3 )

4 ( x² - 9 ) + 4 x = 3 x² + 9 x

4 x² - 36 + 4 x - 3 x² - 9 x = 0

x² - 5 x - 36 = 0