<p>I need help with this question:</p>
<p>How many positive integers are in the range of f(x)=8-2x^2?</p>
<p>Just graph the equation with your calculator. You will see that the graph crosses the x-axis at about (-2,0) and (2,0). Since range represents the Y-coordinate, look for all integer Y-coordinates on the graph above the x-axis (the question only wants positive integers); there are 8.</p>
<p>The "right" way to do the problem would be to realize that 8-2x^2 = -2x^2 + 8. Knowing your parent graphs, you would realize that -2x^2 is a upside-down parabola with a vertex at (0,0). Adding 8 to that function would move it up 8 units and thus give 8 integer y-coordinates above the x-axis.</p>
<p>This function is gonna be a parabola, opening downward, with its vertex at (0,8). The range of a function is its set of y values, in this case everything from negative infinity to 8. But this question only wants the positive integers in the range, so that means 1,2,3,4,5,6,7,8. That's 8 integers. Is that the right answer?</p>
<p>Yeah, that's basically what I said.</p>
<p>yes that is and thank you all for your help</p>
<p>functions and graphs are still killing me</p>
<p>Those can be a really pain in the butt on the SAT II math, but on the SAT I, they're not so bad.</p>