To solve by substitution, Holly, we need to solve either one of the two above equations for either x or y, and then substitute that value of x or y into the other remaining equation. Let's choose to solve the second equation for x.
3x + 8y = -6
3x = -6 - 8y
x = -2 - 8/3 y
Now, we can substitute x = -2 - 8/3 y into the top equation
-2x - 5y = 3 becomes
-2(-2 - 8/3 y) - 5y = 3
Now, solve this equation for y. Once you have the numerical value for y, you can plug it into either of the two equations to obtain the numerical value of x. Can you handle it from here, Holly?
Holly O.
Yes thank you
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01/09/17
David W.
Checking (very important):
-2x-5y=3 -2(-6/31)-5(-21/31) = 3 ? 12/31+105/31 = 3 ? 117/31 = 3 ? 3 24/31 = 3 ?No
3x+8y=-6 3(-6/31)-8(-21/31) = -6 ? -18/31-168/31 = -6 ? -150/31 = 3 ? -4 26/31 = 3 ?No
3x+8y=-6 3(-6/31)-8(-21/31) = -6 ? -18/31-168/31 = -6 ? -150/31 = 3 ? -4 26/31 = 3 ?No
The importance of checking your work (and of checking the work of others) is severely underrated!!
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01/09/17
Michael A.
tutor
LOL, very true David W. To Holly, you're very welcome. I hope that you arrived at x = 6 and y = -3.
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01/09/17
Mayuran K.
01/09/17