You may want to review solving quadratic equations first.
Quadratic functions can also appear in the form y = −4 ⁄ 7 * (x + 2)2 + 1 ⁄ 5. Now, to find the y-intercept, just plug in 0 for x. (The answer will be −73 ⁄ 35.) To find the vertex is now very easy; it's just −2. In general, just take whatever's added to x and take the additive inverse of it (so if it had been x − 2 then it would be 2).
The roles of x and y can be reversed. In that case, to find the x-intercept, you plug in 0 for y.