Select the letter of the correct answer.
2 answers:
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Answer:
77. Proved
78. Proved
79. Proved.
80. Proved.
Step-by-step explanation:
77. Left hand side
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=
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{Since we know, }
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= Right hand side (Proved)
78. Left hand side
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{Since }
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= Right hand side (Proved)
79. Left hand side
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{Since }
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= Right hand side
80. Left hand side
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{Since }
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= Right hand side. (Proved)
Answer:
yes
Step-by-step explanation:
The line intersects each parabola in one point, so is tangent to both.
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For the first parabola, the point of intersection is ...
y^2 = 4(-y-1)
y^2 +4y +4 = 0
(y+2)^2 = 0
y = -2 . . . . . . . . one solution only
x = -(-2)-1 = 1
The point of intersection is (1, -2).
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For the second parabola, the equation is the same, but with x and y interchanged:
x^2 = 4(-x-1)
(x +2)^2 = 0
x = -2, y = 1 . . . . . one point of intersection only
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If the line is not parallel to the axis of symmetry, it is tangent if there is only one point of intersection. Here the line x+y+1=0 is tangent to both y^2=4x and x^2=4y.
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Another way to consider this is to look at the two parabolas as mirror images of each other across the line y=x. The given line is perpendicular to that line of reflection, so if it is tangent to one parabola, it is tangent to both.
