-2(x + 5) = 4, what is x?
2 answers:
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Answer: By the slope formula.
Step-by-step explanation:
Given: ABC is a triangle (shown below),
In which A≡(6,8), B≡(2,2) and C≡(8,4)
And, D and E are the mid points of the line segments AB and BC respectively.
Prove: DE║AC and DE = AC/2
Proof:
Since, And, D and E are the mid points of the line segments AB and BC respectively.
Therefore, By mid point theorem,
coordinate of D are
Coordinate of E are
By the distance formula,
By the slope formula,
Slope of AC =
Slope of DE =
Statement Reason
1. The coordinate of D are (4,5) and 1. By the midpoint formula
the coordinate of E are (5,3)
2. The length of DE = √5 2. By the Distance formula
The length AC = 2√5 ⇒ Segment DE
is half the length of segment AC
3. The slope of DE = -2 and the 3. By the slope formula
slope of AC = -2
4. DE║AC 4. Slopes of parallel lines are equal
To solve the problem, substitute the given points for x in the given equation to get
Solving the three equations simultaneously, we have:
a = -3, b = 2 and c = -5
Therefore, the required equation is
Solving the three equations simultaneously, we have:
a = -3, b = 2 and c = -5
Therefore, the required equation is