C, An approaching storm would be a foreshadow of something bad happening
Answer:
I would think that this is referring to a pastry :)
Explanation:
I like to cook/bake
<span><span>y^2 </span>+ 4xy + <span>x^2 </span>= 13
</span>
<span><span>f^2</span>(x) + 4x f(x) + <span>x^2 </span>= 13
</span>
<span>2f(x)<span>f′</span>(x)+4(f(x)+x<span>f′</span>(x))+2x=0
</span> more easiliy written as
<span><span>2y<span>y′</span>=4(y+x<span>y′</span>)+2x=0</span></span>