Question

Find the axis of symmetry for the following function.
f(x) = -2x2 - 4x

x=?

Answer 1

hold on im gonna look in my notes

Answer 2

well that was wrong. vertex is
\[-\frac{b}{2a}=-\frac{4}{4}=-1\]

Answer 3

how would i find the y-intercept of this problem?

Answer 4

y = -2(x^2 + 2x)
y = -2(x^2 + 2x +1 - 1) *divide the middle number by two then square it (subtract and add that number)

y = -2 (x^2 + 2x + 1) +2 *take the subtracted number and multiply it by a to move it out of the brackets

y = -2(x + 1) ^2 + 2 *take the middle term and divide it by 2 to get the x value. then square the whole bracket

your vertex is (-1, 2) * h value is always opposite of the sign

Answer 5

x = -1 <----- axis of symmetry

as for your y - intercept set all your x values to 0 and solve for y

y = -2x^2 - 4x
y = -2(0)^2 - 4(0)
y = 0 * your y intercept is 0

Note f(x) is y

Answer 6

y intercept, set it equal to zero and solve get
\[-2x^2-4x=0\]
\[-2x(x+2)=0\]
\[x=0,x=-2\]