Answer:
The sum of the first twenty-seven terms is 1,188
Step-by-step explanation:
we know that
The formula of the sum in arithmetic sequence is equal to
where
n is the number of terms
a1 is the first term
d is the common difference (constant)
step 1
Find the common difference d
we have
n=7
a1=-8
S=28
substitute and solve for d
step 2
Find the sum of the first twenty-seven terms
we have
n=27
a1=-8
d=4
substitute
As the general formular for a straight line is
m represents the gradient
c represents the point at which the line crosses the y axis.
Therefore you simply plug the numbers into the equation.
You can work out whether 2 lines are perpendicular by multiplying their gradients. The product of the gradient of perpendicular lines will always be -1.
If lines are perpendicular, M1× M2 = − 1
So you can rearrange the equation to get M2=-1/M1.
As they perpendicular they have to intercept at the same point on the Y axis therefore you get the equation
Explanation is in a file
bit.ly/3a8Nt8n
Third one is true and x is 22,000
hope this helps