Answer:
D
Step-by-step explanation:
Firstly, since it is a selection question, we shall be using a combination approach.
So here we are trying to select the best answer that describes that 2 out of 10 students are selected.
Let’s consider the scenario below;
selecting r out of n can be resolved using the combination nCr
= n!/(n-r)!r!
Now in this case, our n = 10 and r = 2.
Thus, 10C2, we have ;
10!/(10-2)!2! = 10!/8!2! = (10 * 9 * 8!)/8!2! = (10 *9)/2! = 90/2 = 45
Thus, 10C2 = 45
Here, the order of selection does not matter as we can select in random fashion. This makes option D correct
4x + 3y = 5...(1)
2x + 3y = 1...(2)
(2)*2:
4x+6y=2...(3)
(1)-(3):
4x+3y-(4x+6y)=5-2
4x+3y-4x-6y=3
-3y=3
y=-1
By sub. y=-1 in (2), we have
2x+3(-1)=1
2x-3=1
2x=4
x=2
The solution is x=2,y=-1
Answer:
3x-6y
Step-by-step explanation:
3/4(4x-8y)
3/4×(4x-8y)
3/4×4(x-2y)
3×1(x-2y)
3x-6y
Answer:
x = -5
y = -5
Step-by-step explanation:
If you multiply the top equation by negative 2, you can add it to the bottom equation and cancel out the x:
-2(-x + 5y = -20) --> 2x - 10y = 40
Add this to the bottom equation top to bottom:
2x - 10y = 40
-2x + 4y = -10
You get:
-6y = 30
Then solve for y:
y = -5
Plug this back in for either equation and solve for x:
-x + 5(-5) = -20
-x -25 = -20
-x = 5
x = -5
Your answers are:
x = -5
y = -5
Answer:
a
Step-by-step explanation:
