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Writing Equations of Lines
Exit Ticket
1) Write the equation of a line parallel to y=2x+9 that passes through (4,7).
• First find the slope!!!!
• The slope given is 2. Since the equation must be parallel the slope used must be 2.
1) Write the equation of a line parallel to y=2x+9 that passes through (4,7).
• Therefore m=2 and the point (4,7) are x and y respectively.
• Substitute y, m, and x in y=mx+b.7=2(4)+b (Note that the letter b stays in the equation. 9 is not used.)
Use this to find the new b!
1) Write the equation of a line parallel to y=2x+9 that passes through (4,7).
Use this to find the new b!
7=2(4)+b (Note that the letter b stays in the equation. 9 is not used.)
7 = 8+b-8 -8-1= b
1) Write the equation of a line parallel to y=2x+9 that passes through (4,7).
What is our new b???
b=-1
1) Write the equation of a line parallel to y=2x+9 that passes through (4,7).
b=-1So our equation is…
y= 2x+ -1 m b
2) Write an equation that is perpendicular to y= -1/4 x+1 and goes through ( 4,2).
• First find the slope!!!!
• The given slope is -1/4.
• What is the perpendicular slope??????
•m= - ¼ perpendicular m= + 4
2) Write an equation that is perpendicular to y= -1/4 x+1 and goes through ( 4,2).
• With m= 4 and the point (4,2) we can write the equation.
• Write the formula y=mx+b.
• Then substitute y, m, and x and then solve for
the new b.
2) Write an equation that is perpendicular to y= -1/4 x+1 and goes through ( 4,2).
• With m= 4 and the point (4,2) we can write the equation.
• Then substitute y, m, and x and then solve for
the new b.• y=mx+b• 2=4(4)+b
2) Write an equation that is perpendicular to y= -1/4 x+1 and goes through ( 4,2).
• y=mx+b• 2=4(4)+b
2 = 16+b - 16 -16- 14=b
2) Write an equation that is perpendicular to y= -1/4 x+1 and goes through ( 4,2).
B=4So our equation is…
y= 4x+ -14 m b
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