Instructions: Select the correct answer.
2 answers:
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Answer:
740
Step-by-step explanation:
The n th term of an arithmetic series is
= a₁ + (n - 1)d
where a₁ is the first term and d the common difference
Given a₃ = 7 and a₇ = (3 × 7) + 2 = 21 + 2 = 23 , then
a₁ + 2d = 7 → (1)
a₁ + 6d = 23 → (2)
Subtract (1) from (2) term by term
4d = 16 ( divide both sides by 4 )
d = 4
Substitute d = 4 into (1)
a₁ + 2(4) = 7
a₁ + 8 = 7 ( subtract 8 from both sides )
a₁ = - 1
The sum to n terms of an arithmetic series is
=
[ 2a₁ + (n - 1)d ] , thus
=
[ (2 × - 1) + (19 × 4) ]
= 10(- 2 + 76) = 10 × 74 = 740
Therefore the equation of the line in function-form is f(x)=-2x-1
An equation of a line on the cartesian plane is given by y=mx+c. Here m denotes the slope of the line and c denotes the y-intercept.
Slope of a line is defined as the inclination of the line along the positive x- axis . Slope is calculated by the formula where
and
are two points on the line.
y-intercept is defined as the point where the line passes through the y-axis.
From the graph we can see that the line passes through (0,-1)and (-1,1)
therefore slope of the line is
Now we know that the equation of a line passing through a point and with slope m is given by
Substituting the values in the equation we get
y-(-1)=-2(x-0)
or, y=-1-2x
Therefore the equation of the line in function-form is f(x)=-2x-1 .Hence the second option is correct.
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