If you want to shift the graph of a function horizontally left, then you add some amount to the x-value. If a horizontal right shift is needed, then you subtract from the x-value.
Furthermore, if you wish to move your graph vertically up, then add to the y-value (the function itself). And subtract from it for a vertically down shift.
Now, we need a horizontal 3 unit left shift. That means we add 3 to the x-value, without touching the function itself. The function is [tex]\mathrm{F}(x)=x^2[/tex], hence the shifted function is [tex]\mathrm{G}(x)=(x+3)^2[/tex].
