answersLogoWhite

0


Best Answer

The question refers to the equation of a parabola, that is, a quadratic equation of the form y = ax2 + bx + c.

Suppose x1 = -b/2a - z

and x2 = -b/2a + z for some real number z.

Then

y1 = a*(-b/2a - z)2 + b*(-b/2a - z) + c

= b2/4a + bz + az2 - b2/2a - bz + c

= b2/4a + az2 - b2/2a + c

and

y2 = (-b/2a + z)2 + b*(-b/2a + z) + c

= b2/4a - bz + az2 - b2/2a + bz + c

= b2/4a + az2 - b2/2a + c

So y1 = y2

thus, if x is the same distance (z) either side of -b/2a, then the corresponding y values are the same. And that, is what a line of symmetry means.

User Avatar

Wiki User

12y ago
This answer is:
User Avatar

Add your answer:

Earn +20 pts
Q: Why is the equation of the line of symmetry x equals negative b over 2a?
Write your answer...
Submit
Still have questions?
magnify glass
imp
Related questions

What is an equation of the axis of symmetry of the parabola represented by y equals -x2 plus 6x-4?

Line of symmetry: x = 3


What is the formula for finding the line of symmetry for a quadratic equation?

the formula is negative b divided by 2 times a


What is the line of symmetry for the parabola whose equation is y equals 3x2 plus 24x - 1?

Vertical line of symmetry cuts through x = -4 - (sqrt of 3)


What is the line of symmetry for the parabola whose equation is y equals -x2 plus x plus 3?

For a quadratic equation y=Ax2+Bx+C, the line of symmetry is given by x=-B/2ASo for the equation y=-x2+x+3, B is 1 and A is -1, so the line of symmetry isx=1/2


What is the equation of symmetry of y equals 2x plus 12x - 5?

It is a straight line equation with a slope of 14 and a y intercept of -5


What is the line of symmetry for the parabola whose equation is y equals x2 - 12x plus 7?

At: x = 6


What is the slope of a line which is perpendicular to the line that has an equation of y equals x plus 13?

negative 1


What is the line of symmetry for the parabola whose equation is y equals x2 plus 10x plus 25?

When x = -5


Y equals ax2 - 2x - 3 The line of symmetry is x equals 1 Does an equal 1 or -1 or 2?

For the equation ax2-2x-3, the quadratic coefficients are:a=a,b=-2c=-3.The equation of the line of symmetry is:x= -b/2aAs we know that the line of symmetry is x=1,we get:1 = 2/2a, so2a = 2and a = 1.We get a bowl-shaped parabola, whose lowest point is (1,-4).


What is the equation of the straight line that passes through (82) and (8 -3)?

Find an equati find an equation for the line perpendicular to the line 8x - 8 y equals negative 2 having the same Y intercept as -6x + 2 y equals negative 8


An equation of a parabola that has x equals 2 as its axis of symmetry is?

How about y = (x - 2)2 = x2 - 4x + 4 ? That is the equation of a parabola whose axis of symmetry is the vertical line, x = 2. Its vertex is located at the point (2, 0).


What is the equation of the axis of symmetry y equals x2 - 8x plus 16?

y = (x-4)(x-4) * * * The factors above are shown correctly. The axis of symmetry is the vertical line passing through the vertex, which is the point located at (4, 0). The equation of that line is x = 4, which is the answer you requested.