In the equation above, k is a constant. If y = 17 when x = 2, what is

Question

y = kx + 3

In the equation above, k is a constant. If y = 17 when x = 2, what is the value of y when x = 4 ?

(A) 34
(B) 31
(C) 14
(D) 11
(E) 7

Bunuel · Answer

SOLUTION

y = kx + 3

In the equation above, k is a constant. If y = 17 when x = 2, what is the value of y when x = 4 ?

(A) 34
(B) 31
(C) 14
(D) 11
(E) 7

Since if  y = 17  when  x = 2 , then  17 = 2k + 3  -->  k=7 .

Thus,  y = 7x + 3 . When  x=4 ,  y = 7*4 + 3=31 .

Answer: B.

carcass · Answer

y = kx + 3  is the equation of the slope but in this context the question is different

y = K * 2 + 3 to have y = 17 then K must be   7

17 = 7*2 + 3

y = 7*4 + 3  --->  y = 31

B must be the answer.  Sub 600

Thanks

fameatop · Answer

Answer is B. 
Same explanation as Carcass's

Muki · Answer

Answer is B (=31)

Explanation is same as provided by Carcass above.

ratinarace · Answer

1) Put y =17 and x=2 and solve for K
2) Knowing k=7 from above and x=4 solve for Y ------> Y=31

Answer is B

bhavinshah5685 · Answer

1 st step : solve given eqn for K by putting values of x and y. u get k=7
snd step : now put banck value of k=7 and x=4 in given eqn and solve for y.
you get y=31

so Y=31 answer

mbaiseasy · Answer

y = kx + 3 
 17 = k(2) + 3 --> 14 = 2k --> k=7

y = (7)(4) + 3 --> y = 31

Answer: B

luckyme17187 · Answer

given
y=kx+3

y=17 ; x=2

k = 4.

y=? if x = 7

y=31

JeffTargetTestPrep · Answer

We are given the equation y = kx + 3, where k is a constant.

We are also given that y = 17 when x = 2, so we can plug these values into the equation to first determine a value for k. 
y = kx + 3

17 = 2k + 3

14 = 2k

k = 7

We now can determine the value of y when x = 4:

y = kx + 3

y = (7)(4) + 3

y = 28 + 3

y = 31

The answer is B.

adiagr · Answer

Given: y = kx + 3
Putting values of y and x.

17 = 2k+3; 2k = 14;  k = 7 .

Once k is known, I can calculate y for any value of x.

y = kx + 3
 = {(7) * 4} +3
 = 31

B is the answer

syahasa2 · Answer

The approach is right as seen above.
But I doubt that this question is a 600 difficulty question.
Maybe sub-600 more obviously.

DharLog · Answer

y = kx + 3

In the equation above, k is a constant. If y = 17 when x = 2, what is the value of y when x = 4 ?

(A) 34
(B) 31
(C) 14
(D) 11
(E) 7

May as well to use such approach:
If y = 17 when x = 2 -> 17 = 2k+3
When x = 4, y = 4k+3 =  2*(2k+3)-3=2*17-3=31 
The answer is B.

abrahamic · Answer

My approach inspired by a video I saw on GMATPrepNow was pretty quick.
I saw the y intercept in the equation "y = kx + 3" = 3 which implies coordinate (0,3)
Then the question gave away another coordinate (2,17) which shows that there was a 14 point rise in y with a 2 point run in x
Hence, another 2 point run in x makes x=4 and y=17+14=31

gupta335 · Answer

y = kx + 3

In the equation above, k is a constant. If y = 17 when x = 2, what is the value of y when x = 4 ?

17=2K+3
K=14/2=7

y=7*4+3=31

Abhishek009 · Answer

y = kx + 3

Substitute  y = 17  &  x = 2  in the above equation

Or,  17 = k*2 + 3

Or,  2k = 14

Or,  k = 7

Substitute x = 4 in the equation  y = kx + 3

Or,  y = 7*4 + 3

So,  y = 31 , Answer must be (B)

hasnain3047 · Answer

y=kx+3 
 17=2k+3 
 k=7 
now
 y=4*7+3 
 y=31

Kinshook · Answer

y=kx+3
17 = 2k +3
k= 7

y = 4*7+3=28+3=31

IMO B

Posted from my mobile device

ArtemNYC · Answer

Hey guys! 
I must have not seen here any explanation from the equity.

Look closer, if 2k and 4k are similar with the coefficient 2, i.e. 2*2k, it means that all equation might be similar multiplied by 2. So we understand that y must be doubled and 3 points less (because there is a sum on the right): 17*2-3 = 31. Easier, quicker and logical.

What do you think?

LUBABAYIMER · Answer

y=kx+3
then 17=2k+3
17-3= 2k
14=2k both divided by 2 then k=7 therefore
when x=4
y=7*4+3   /c k is constant
y=31 the answer is B

In the equation above, k is a constant. If y = 17 when x = 2, what is

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In the equation above, k is a constant. If y = 17 when x = 2, what is

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

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