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Mathematics 7 Online
mikewwe13:

Select the correct choices that belong in the blank for the system of equations shown below. 24x - 39 = 165 -6x +13y = -51 In order to solve this system by elimination, Stacy ____________ by ______. Then, when she adds the equations together, the x terms will cancel. A. multiplies the second equation; 4 B. multiplies the second equation; -4 C. multiplies the first equation; 4 D. multiplies the first equation; -4

mikewwe13:

@Vocaloid

dude:

For systems of equations you want to get rid of one variable, lets get rid of x You would need 24x and -6x to both be either \(+24, -24\). Since we use addition to get rid of a variable we need -6x to remain negative. How would you get -6x to be -24x?

mikewwe13:

The coefficients of the terms must be opposites, so they will have a sum of 0.

mikewwe13:

If you want a pair of terms to cancel when you add two equations together, what must be true about the coefficients of those terms?

mikewwe13:

The opposite of 24 is −24.

dude:

Right, so \(-6\cdot x=-24?\)

mikewwe13:

x = 4

dude:

We can remove B and D, since we are multiplying -6 by 4 We must also multiply everything else in that equation by 4, which is the second equation

mikewwe13:

A. multiplies the second equation; 4

dude:

Yep

mikewwe13:

THANKS A LOT MAN

dude:

Sure :)

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