I'm at such a loss.
In exercise 4 I don't even know where to being, and in exercise 9 the x=a confuses me.
Thanks in advance
4a) We have $\displaystyle 2x+y=6; x=1 \implies y=4$
Also we know the gradient; $\displaystyle m=-2$
Differentiate $\displaystyle y=x^2+ax+b$
$\displaystyle \implies \frac {dy}{dx} = 2x+a$
$\displaystyle \implies 2x+a=-2$
$\displaystyle x=1; 2(-1)+a=-2$
$\displaystyle \implies a=0$
$\displaystyle \implies y=x^2+b$
$\displaystyle x=1, y=-4; -4=1^2+b$
$\displaystyle \implies b=-5$
b is similar so ill let you try.