Graphs and Relations Questions

[jsimmo]

Hey, I just have a few questions that I need help with:

Question 1


Question 2


Question 3

[clinton_09]

for question 3 (a) the answer is B because 25x goes into 450 18 times which works out to be what is pictured on the x axis. 18y goes into 450 25 times which is shown on the y axis 25. you can tell it is > because by using (0,0) as a test point 25(0) + 18(0) = 0 which is not greater than 450. therfore you shade underneath the blue line which is pictured.

(b) to work this out you sub the value 20 into the y values an 0 into the x values. The answer is A because 2(0)+5(20)=100
                                                                                                                                                   0+100=100.


Hope thats clear for you

[Mao]

question 1:

x-intercept is when y=0:
substituting y=0, we notice that both A and B are false

y-intercept is when x=0
substituting x=0, we notice that E is false

since the white region is the one required, we substitute a point in the white space, in this case, (0,0) because it is the easiest.

correct answer is D


Question 2:
option D and E are obviously false, as the required region is white and they are less than 10

we can also see that inequality given by the question has axis intercept at (0,0), and this is obviously the increasing line.
this invalidates the second inequality in option A, as that also has axis intercept at (0,0).

we are left with B/C, and substituting (0,5) gives us the correct answer B


Question 3:
looking at option C and D, their x-intercept will be at 125/9=13.8888, this is obviosly false.

option A and B both satisfy this, and since the white space is above it, we know that all numbers above this line will satisfy the inequality [we are not worried about the other inequalities]
substituting (20,20) gives us option B as the correct answer

for part b, substituting (0,20) gives you A as the correct option.

[jsimmo]

for question 3 (a) the answer is B because 25x goes into 450 18 times which works out to be what is pictured on the x axis. 18y goes into 450 25 times which is shown on the y axis 25. you can tell it is > because by using (0,0) as a test point 25(0) + 18(0) = 0 which is not greater than 450. therfore you shade underneath the blue line which is pictured.

(b) to work this out you sub the value 20 into the y values an 0 into the x values. The answer is A because 2(0)+5(20)=100
                                                                                                                                                   0+100=100.


Hope thats clear for you

Question 3A: I still don't understand it fully..

Also, for Question 3B: You can do the same method to D and it works out the same??

[clinton_09]

3B) D and A are not the same because 5(0)+2(20)
                                                      0+40=40    not 100