Solve the problem.
-If a cross-section of the parabolic mirror in a flashlight has the equation $y ^ { 2 } = 7 x$ x, where should the bulb be placed?
A) $\frac { 7 } { 4 }$ units to the left of the vertex
B) $\frac { 7 } { 2 }$ units to the right of the vertex
C) $\frac { 7 } { 4 }$ units to the right of the vertex
D) $\frac { 7 } { 4 }$ units above the vertex

Question

Solve the problem.
-If a cross-section of the parabolic mirror in a flashlight has the equation $y ^ { 2 } = 7 x$ x, where should the bulb be placed? 
A) $\frac { 7 } { 4 }$ units to the left of the vertex
B) $\frac { 7 } { 2 }$ units to the right of the vertex
C) $\frac { 7 } { 4 }$ units to the right of the vertex
D) $\frac { 7 } { 4 }$ units above the vertex

Quizplus · Accepted Answer

The bulb should be placed at the focus of the parabolic mirror. For a parabola in the form $y^2 = 4ax$, the focus is at $(a, 0)$. Here, $4a = 7$, so $a = \frac{7}{4}$. Therefore, the bulb should be placed $\frac{7}{4}$ units to the right of the vertex.

Solve the Problem y2=7xy ^ { 2 } = 7 xy2=7x

Solve the Problem $y ^ { 2 } = 7 x$