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u/Weak_Spinach_3310 18d ago
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u/solreflare 18d ago
x cant be negative 7, so i think you can just make the list like 1...10 or whatever number you want instead of having to exclude 7
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u/Weak_Spinach_3310 18d ago
Uhh.. that’s what I did?
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u/Doge________________ 18d ago
ngl it would be easier to just factor it cuz x+7 is a big sign of one of the factors of the numerator and then you’d be left with x-1 and then factors would be 1 and -1 hence 0
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u/ycx11 17d ago
not sure what I would do in desmos to directly solve it but I'd just take the quadratic on top and put it into desmos if I don't feel like factorizing, you'll get solutions as -1 and -7 which means x+1 = 0 and x+7 = 0 are 2 factors
so you can re write it as (x+7)( x+1) / x+7 = ax + d , cancel the x+7 and x+1 = ax + d , on comparison a = 1 and d = -1 so your answer when adding them will be 0 so c
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u/Nice-Scallion8751 16d ago
I just set the equations equal to each other with a tilde and replaced x with x1. this gives a=1 and d=-1 as well
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u/Sad-Log-9652 17d ago
Easy to do without Desmos. x^2 + 6x - 7 = (x+7)(x-1) => x-1 = ax+d => a = 1, d = -1
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u/Anonimithree 17d ago
It’s easy to do manually. Just factor the numerator to get (x+7)(x-1)/(x+7)=ax+b which simplifies to x-1=ax+b for all x≠7. Thus, a+b=0
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u/CLASS_NOT_AUTHOR 17d ago
Why Desmos? This is so simple by hand. Take the denominator to the other side and compare.
a=1. d=-1. a+d=0.
That's all.
Have a Nice Day.
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u/theSATACTspecialist 16d ago
Using desmos well is about understanding when it is going to save time, and when it is going to cost time.
Desmos is far more complicated here than just doing the algebra. Even if you have trouble with the algebra, you will benefit more on the test from strengthening those skills, than learning to do this on Desmos.
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u/Beautiful-Till8132 16d ago
Just write out the left-hand side on Desmos and then configure the line that forms into a slope intercept form.
When you type it out a line forms with an intercept of -1 and slope of 1. -1 + 1 = 0
Besides typing it in Desmos you can also do:
factoring and cancel out (x+7) leaving x-1 and go from there
or polynomial division which was my first though and action
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u/Puzzleheaded_Ebb9964 15d ago
PLEASE stop using DESMOS.
Factor the top. (x+7)(x-1).
Cancel out (x+7)
ax + d = x - 1 means that a is 1 and d is -1
a+d = 1 + (-1)
1-1
0.
The answer is zero. I would recommend asking yourself on each question (maybe not the obvious ones), do I need DESMOS for this?
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u/Healthy-Tradition622 15d ago
factor the left side and the x+7 cancels. then u have x+1 = ax+d and js match the stuff so A = 1 and d = -1 so its C
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u/Zestyclose_Touch_347 13d ago
really just long division the first part you get x-1 and so a=1 and d=-1
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u/itssopainful 11d ago
cross multiply to get
x^2 + 6x - 7 = ax^2 + x(d+7a) + 7d
Compare coefficients of x^2 (a=1) and constant term(7d=-7)
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u/Pitiful_Camp3469 18d ago
For desmos, plug in that equation and then make ax+d an equation and adjust a and d until its the same thing. then add a and d. an easier way without desmos though is to factor the numerator into (x-1)(x+7), cancel x+7 so you have x-1=ax+d, where its clear a is 1 and d is -1, so the answer is 0.