Determine whether y varies directly with x, If so, find the constant of variation k and write the equation.
x y
4 6.4
7 11.2
10 16
13 20.8
Would like for someone to explain if possible
6.4 = k*4
k = 6.4 / 4
k = 1.60
11.2 = k * 7
k = 11.2 / 7
k = 1.60
16 = k * 10
k = 16/10
k = 1.60
20.8 = k * 13
k = 20.8/13
k = 1.60
Assume y varies direct with x
then y = kx
testing with (10,16)
16 = 10k
k = 1.6
so your equation would be y = 1.6x
check if true for the other points
e.g. the last one ...
x = 13, y = 20.8
is 20.8 = 1.6(13) ? , YES
check if true for all points, if so,
then y varies directly with x and
y = 1.6x
2.
y = kx
Substitute y with -252 and x with 84
-252 = k(84)
It's easy to find k now
k = -3
Now do it again, but substitute x with 74, and k with -3
y = -3(74)
y = -222
3.
We have the original equation, so all we have to do is substitute x!
f(4) = 4 (4) + 7
Multiply the right side
f(4) = 16 + 7
Now just add and you'll have your output!
f(4) = 23
Hope this all helped!
It's the right answer i am sure :), good luck !, if you have an questions please let me know, i am here to help ! ^V^
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I think you are saying I need to figure each set of numbers like you did for every number set and they do.But how do you know which number set to start with or write the equation? I got the same answers by divivding the number sets.
They're right! I'll post the answers for the other quiz too. Keep in mind I'm in honors tho!
1) A. Domain: (-4,-1,1,4); Range: (-1,1,4); Yes, the relation is a function.
2) D. 30t + 2.75; $152.75
3) C. 327.6 mi
4) A. 5
5) B. y = 2/7x - 12
6) C. Passes through (0,-2) (1,0)
7. C. y - 15 = -3(x + 2)
8. D. y + 8 = 3 (x - 8)
9. A. 17x + 10y = 85
10. D. x-intercept: (3,0)
y-intercept: (0,5)
11. C. y = 9/5x + 32
12. C. y = -9/4x + 12