(a) (i) In first 4 minutes Mary's speed was 600 / 4 = 150 m / minute
(ii) in last 4 minutes her speed was (1000-600) / 4 = 400/4 = 100 m/min
(b) Marys average speed for the whole journey = 1000/8 = 125 m/min
(c) 200 m
(d) Peter arrived at school after 7 minutes . Mary took 8 minutes. Peter first.
(e) Where they met is given by where the 2 curves intersect. That is at time 6.8 minutes and 880 m from Mary's home
(f) At t= 4 dsitance between then is 600 - 400 = 200 m
The solution (x,y) needs to work in both equations. With multiple choice you can do guess and test method. Otherwise you need to combine the two equations into one by substitution or elimination methods.
21. substitution works well here since one equation is y= x+3. you can easily substitute the (x+3) for y in the other equation.
2x + (x+3) = -6
3x + 3 = -6
3x = -9
x = -3
use this in either equation to find y.
y = (-3)+3
solution: (-3,0)
22. these both equal y so they equal each other.
4x - 1 = 3x +6
4x - 3x = 6 + 1
x = 7
use this in either equation to find y
y = 4(7) - 1
y = 28 - 1
y = 27
solution: (7,27)
23. one equation is y = 2x - 3. So substitute (2x -3) for y in the other equation.
4x = 2(2x - 3) + 6
4x = 4x - 6 + 6
4x = 4x
x = x
any solution will work, infinitely many.
24. infinitely many solutions means the two equations are the same equation. Like the previous one they didn't look the same but if you put them both in terms of y...
y= 2x-3
4x = 2y + 6
4x - 6 = 2y
(4x - 6)/2 = y
2x - 3 = y
same equation.
from the image, I can't see all options but A & C do not look like the same equations. It's got to be either B or D.
Answer:
d+5 or 5+d
Step-by-step explanation:
Sum means to add so if we add the two we get d+5
