Which coefficien in the function y=-2x^2+5x-4 tells us that the parabola opens downward? @satellite73

Question

anonymous · Answer

the "leading coefficient' which is the number in front of the $x^2$ term

anonymous · Answer

in this case it is $-2$ and since $-2$ is negative, the parabola opens down

anonymous · Answer

WHAT ABOUT THIS ONE ? What are the x-intercepts for the equation: y = x2 + 3x − 4

anonymous · Answer

$$y=x^2+3x-4=(x+4)(x-1)$$ set $x+4=0$ and $x-1=0$ just like before
you get $x=-4$ or $x=1$

anonymous · Answer

$x$ intercept is a synonym for the "zeros" i.e. set it equal to zero and solve, like last night

anonymous · Answer

-3,4?

anonymous · Answer

no no $-4,1$

anonymous · Answer

oh okay got it help me with this last one please Which quadratic equation has a vertex of (1.5, 4.25) and opens downward?

anonymous · Answer

do you have a choice that looks like 
$$y=-(x-1.5)^2+4.25$$?

anonymous · Answer

no

anonymous · Answer

or $y=-x^2+3x+2$ ?

anonymous · Answer

got that choice?

anonymous · Answer

if not let me see the choices, but i bet you have 
$$y=-2x^2+3x+2$$

anonymous · Answer

What is the vertex of the function y=x^2-4yx+3 help me with this pleassseeee

anonymous · Answer

what is that $y$ doing there?  a typo?

anonymous · Answer

$$y=x^2-4x+3$$ is that it?

anonymous · Answer

in this case $a=1, b=-4$ and $-\frac{b}{2a}=-\frac{-4}{2}=2$ first coordinate of the vertex is $2$

anonymous · Answer

second coordinate is what you get when you replace $x$ by $2$
you should get $$2^2-4\times 2+3=4-8+3=-1$$ so vertex is $(2,-1)$

anonymous · Answer

you got that?

anonymous · Answer

yeah i did thanks C:

anonymous · Answer

gotta do better than 70 tonight right?

anonymous · Answer

yup :d my last module so happy