SOLUTION: Which of the following is the equivalent equation to y = 7/9x + 8?
A. 9x - 7y = -72
B. 9x + 7y = -72
C. 7x - 9y = -72
D. 7x + 9y = -72
Algebra.Com
Question 1204341: Which of the following is the equivalent equation to y = 7/9x + 8?
A. 9x - 7y = -72
B. 9x + 7y = -72
C. 7x - 9y = -72
D. 7x + 9y = -72
Found 3 solutions by mananth, math_tutor2020, Alan3354:
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
y = 7/9x + 8
multiply by 9
9y=7x+72
7x-9y=-72 is the option
Answer by math_tutor2020(3817) (Show Source): You can put this solution on YOUR website!
Answer: 7x - 9y = -72 (option C)
Reason
Multiply both sides by 9 to clear out the denominator.
Then we'll rearrange things so the variable terms are on the left hand side (LHS) while the constant is on the right hand side (RHS)
Here is one way to write out the steps
y = (7/9)x + 8
9y = 9*( (7/9)x + 8 )
9y = 9*(7/9)x + 9*8 .... don't forget to distribute all the way through
9y = 7x + 72
9y-7x = 72
-7x+9y = 72
At this point we should be done. In some math textbooks that would be the case.
However, other math textbooks require the standard form Ax+By = C to have A > 0.
It appears that your textbook has this requirement.
To make the x coefficient be positive, multiply both sides by -1
-7x+9y = 72
-1*(-7x+9y) = -1*72
7x - 9y = -72
And we're done.
To check the answer, use Desmos or GeoGebra to graph 7x-9y = -72 and y = (7/9)x+8 to see that they produce the exact same line.
https://www.desmos.com/calculator/edykrshgaz
Another way to check the answer would be to type Solve 7x-9y = -72 for y into WolframAlpha. The result it displays is which is the same as or y = (7/9)x + 8.
https://www.wolframalpha.com/input?i=Solve+7x-9y+%3D+-72+for+y
There are many other CAS (computer algebra system) calculators that can do the same thing.
GeoGebra has a CAS feature. For GeoGebra, the input would be Solve[7x-9y=-72,y].
Do not type that into the normal input bar. Instead you need to switch to CAS mode.
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
Which of the following is the equivalent equation to y = 7/9x + 8?
--------------
It's ambiguous.
Might be
Or
Or
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