Well hmmm does the graph open upwards or downwards? well
is a quadratic, if the leading term's coefficient is negative, Down, if positive, Up
a)
now, let's see the leading term, -x², what's its coefficient? is -1 * x² or -1x², is -1, so is negative, thus is opening downwards
c)
x-intercepts occur, when y = 0, namely y = -x²-4x-3, so setting y to 0
0 = -x² -4x -3 take a common factor of -1, thus
0 = -1 (x²+4x+3) <--- now, if we factor that out, notice, surely you've done many of these by now, so we end up with
![\bf \begin{array}{lcclll} 0=x^2&+4x&+3\\ &\uparrow &\uparrow \\ &3+1&3\cdot 1 \end{array}\\\\ -----------------------------\\\\ 0=(x+3)(x+1)\implies \begin{cases} 0=x+3\implies &-3=x\\ 0=x+1\implies &-1=x \end{cases}](https://tex.z-dn.net/?f=%5Cbf%20%5Cbegin%7Barray%7D%7Blcclll%7D%0A0%3Dx%5E2%26%2B4x%26%2B3%5C%5C%0A%26%5Cuparrow%20%26%5Cuparrow%20%5C%5C%0A%263%2B1%263%5Ccdot%201%0A%5Cend%7Barray%7D%5C%5C%5C%5C%0A-----------------------------%5C%5C%5C%5C%0A0%3D%28x%2B3%29%28x%2B1%29%5Cimplies%20%0A%5Cbegin%7Bcases%7D%0A0%3Dx%2B3%5Cimplies%20%26-3%3Dx%5C%5C%0A0%3Dx%2B1%5Cimplies%20%26-1%3Dx%0A%5Cend%7Bcases%7D)
so, the x-intercepts are at -3 and -1
d)
now, the y-intercepts, just set x = 0
y = -x²-4x-3, settting x to 0 y = -0²-4(0)-3, which is y = -3
so the sole y-intercept is at y = -3
now, let's get on to b)
b)
![\bf \textit{vertex of a parabola}\\\\ \begin{array}{lccclll} f(x)=&-1x^2&-4x&-3\\ &\uparrow &\uparrow &\uparrow \\ &a&b&c \end{array}\qquad \left(-\cfrac{{{ b}}}{2{{ a}}}\quad ,\quad {{ c}}-\cfrac{{{ b}}^2}{4{{ a}}}\right)](https://tex.z-dn.net/?f=%5Cbf%20%5Ctextit%7Bvertex%20of%20a%20parabola%7D%5C%5C%5C%5C%0A%0A%5Cbegin%7Barray%7D%7Blccclll%7D%0Af%28x%29%3D%26-1x%5E2%26-4x%26-3%5C%5C%0A%26%5Cuparrow%20%26%5Cuparrow%20%26%5Cuparrow%20%5C%5C%0A%26a%26b%26c%0A%5Cend%7Barray%7D%5Cqquad%20%0A%5Cleft%28-%5Ccfrac%7B%7B%7B%20b%7D%7D%7D%7B2%7B%7B%20a%7D%7D%7D%5Cquad%20%2C%5Cquad%20%20%7B%7B%20c%7D%7D-%5Ccfrac%7B%7B%7B%20b%7D%7D%5E2%7D%7B4%7B%7B%20a%7D%7D%7D%5Cright%29)
and those are the coordinates, notice a = -1, b = -4 and c = -3
now, for
e)
well, all you have to do is, once you have the vertex, pick an x-value on the left-hand-side of the vertex, get they value for "y", or OUTPUT,
then pick another x-value, on the right-hand-side of the vertex, get the "y" value again, and plot away