The line l contains the points A(4, 5) and B(2, 0) - Leaving Cert Mathematics - Question 4 - 2016
Question 4
The line l contains the points A(4, 5) and B(2, 0). Find the equation of l.
Give your answer in the form ax + by + c = 0 where a, b, and c ∈ Z.
(b) Draw the line k:... show full transcript
Worked Solution & Example Answer:The line l contains the points A(4, 5) and B(2, 0) - Leaving Cert Mathematics - Question 4 - 2016
Step 1
Use a graphic, numeric or algebraic method to find the co-ordinates of l ∩ k
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Answer
To find the intersection of lines l and k, we can substitute the equation from line k into line l:
Start with line k:
x+2y=8
Rearranging gives:
2y=8−x⇒y=4−21x
Substitute into line l:
5x−2y+10=0
Replace y with our expression from line k:
5x−2(4−21x)+10=05x−8+x+10=06x+2=0⇒x=−31
Substituting x back into the equation for y:
y=4−21(−31)=4+61=624+1=625
Thus, the intersection point l ∩ k is:
(3,2)
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