Q6. Given
[tex] y= ax^2 + bx + c[/tex]
the vertex is in between the two zeros; it's
[tex]x=- \dfrac{b}{2a}[/tex]
which we know from the quadratic formula is the midpoint between the zeros.
We get a negative x coordinate when a and b have the same signs. Let's go through the choices.
[tex]y = -3x^2 -7x + 4[/tex] -3 and -7 have the same sign, negative x, CHECK
[tex]y = -3x^3 + 7x - 4[/tex] different signs, nope
[tex]y = 3x^2 -7x + 4[/tex] different signs, nope
[tex]y = 3x^2 + 7x - 4[/tex] same sign, CHECK
1st and 4th choice.
Q7.
The correct first step of evaluating the polynomial at x=3/4 is to substitute 3/4 for x, first choice.
