Question 409559: Good evening,I am in need of help of a certain topic"Linear system using substitution" Can you use these examples to show me step by step?
4x-y=17
-9x+8y=2
Found 2 solutions by Edwin McCravy, ewatrrr: Answer by Edwin McCravy(20056) (Show Source):
You can put this solution on YOUR website!
4x-y=17
-9x+8y=2
Look through both equations to find the term that contains
a letter that has the smallest coefficient (in absolute value).
That is the term -y in the first equation
Solve it for y. Add -4x to both sides:
4x-y=17
-4x -4x
-----------
-y=17-4x
Solve for y by dividing every term by the
coefficient of y which is -1
y=-17+4x
Next take the other equation, the one you haven't used,
-9x+8y=2
and replace y by the right side of the previous equation,
placed in parentheses like this: (-17+4x)
So
-9x+8y=2
becomes
-9x+8(-17+4x)=2
Then you solve that for x
-9x-136+32x=2
Combine like terms:
-136+23x=2
Add 136 to both sides:
-136+23x = 2
136 136
-------------
23x = 138
Divide both sides by 23
x = 6
Go back to the equation
y=-17+4x
and substitute (6) for x
y=-17+4(6)
y=-17+24
y=7
So the solution is x=6, y=7, sometimes written
(x,y) = (6,7)
Edwin
Answer by ewatrrr(24785) (Show Source):
You can put this solution on YOUR website!
Hi
solving "Linear system using substitution"
4x-y=17 OR y = 4x-17 |Need to solve for one variable in either equation
-9x+8y=2 |subsituting for y
-9x + 8(4x-17) = 2
-9x + 32x - 136 = 2
23x = 138
x = 6 and y = 7 (4*6 -17) Ordered pair Pt(6,7) is the solution
CHECKING our Answer***
-9x + 8y =2
-54 + 56 = 2
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