Answer:
see explanation
Step-by-step explanation:
Given the 2 equations
5x + y = 21 → (1)
x - 3y = 9 → (2)
Multiply (1) by 3 and add the result to (2) to eliminate y term
15x + 3y = 63 → (3)
Add (2) and (3) term by term
(x + 15x) + )- 3y + 3y) = (9 + 63)
16x = 72 ( divide both sides by 16 )
x = 4.5
Substitute x = 4.5 into (1) for corresponding value of y
22.5 + y = 21 ( subtract 22.5 from both sides )
y = - 1.5
Solution is (4.5, - 1.5 )
choices? i cant tell without choices
To find the standard error, divide the standard deviation by the square root of the sample size
standard deviation = 7.5
sample size = 25......sqrt 25 = 5
standard error = 7.5 / 5 = 1.5 <==
Step one: divide both sides by -2.3 to get X by itself: X=-.2. :)
