X - 6y=18
2x-3y=9 |*-2
x -6y=18
-4x+6y=-18
----------------
-3x=0, x=0
2x-3y=9
2*0-3y=9
-3y=9, y=-9/3, y= -3
Answer:
27x +42+ 3x²
Step-by-step explanation:
so im learning this rn in class and what you do is FOIL
So its stands for
First
Outside
Inside
Last
(3x+6)(x+7)
(3x+6)(x+7) -- 3x² (if you have x times x it is x to the second power)
(3x+6)(x+7) -- 21x
(3x+6)(x+7) -- 6x
(3x+6)(x+7) -- 42
Now add 21x and 6x
27x +42+ 3x²
you must have added the 21 and 6 incorrectly.
If all 25 questions are different,
When order of selection counts:
P(25,7)
=25!/(25-7)!
=15511210043330985984000000/6402373705728000
=2422728000
When order of selection does not count count:
C(25,7)
=25!/(7!*(25-7)!)
=15511210043330985984000000/(6402373705728000*5040)
=480700