Answer:
Well elimination is basically multiplying a number to make it possible for it to cancel out
We can multiply the first equation by 2
2(x+2y=-1)
This would be
2x+4y=-2
Its still the same thing but just with non simplified numbers
We can now do any method really to solve
I will just do the subtraction method
2x+4y=-2
-2x+y=4
Solve
2x-2x=0
4y-y= 3y
-2-4= -6
3y= -6
Now solve
y=-2
To find x subsitute in “y” and find ”x”.
x+2*-2=-1
x-4=-1
x=3
y= -2
x= 3
Imagine, at the first day you have only one penny. Then tomorrow you have 2 pennies, next day you have 4 (2x2), next day you have 8 (4x2), next day you have 16 (8x2).... and so forth.
It looks like geometric sequence isn't it? (the ratio between the number of pennies that you have from the 2nd day and the 1st day is 2)
So, by using geometric sequence theorem we can total those pennies until day-27
S (total pennies at day-27) = (1)(2^27-1) / 2-1 = 2^26 pennies
So, you have 2^26 pennies.. a big number of pennies huh?=))
{The formula is: S = a( r^n-1) / r-1
Where:
a= the number of pennies that you've got at the 1st day
n= number of days you spent to collect those pennies)
r= the ratio of the number of pennies}
For 13 a 0 degree line is a straight line
1st marble is blue is 4/10
2nd marble is blue is 3/9
Multiple together and the probability is 12/90 or 2/15
