SOLUTION: How can i find the y-intercept using x=0 in the quadratic y= 2x^-5x-3? do I use the formula -b/2a to find the vertex for x or y=ax^2+bx+c or both? I need very clear instructions fo

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: How can i find the y-intercept using x=0 in the quadratic y= 2x^-5x-3? do I use the formula -b/2a to find the vertex for x or y=ax^2+bx+c or both? I need very clear instructions fo      Log On


   

Question 555500: How can i find the y-intercept using x=0 in the quadratic y= 2x^-5x-3? do I use the formula -b/2a to find the vertex for x or y=ax^2+bx+c or both? I need very clear instructions for this because i simply don't understand, sorry.
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
1) y+=+2x%5E2-5x-3
To find the y-intercept, simply replace every x in the equation with 0 and evaluate.
y+=+2x%5E2-5x-3 Substitute x = 0.
y+=+2%280%29%5E2-5%280%29-3
y+=+-3 The curve (a parabola) intercepts the y-axis at (0, -3).
2) To find the x-coordinate of the vertex, us -b%2F2a where a = 2 and b = -5.
x+=+-%28-5%29%2F2%282%29 Evaluate.
x+=+5%2F4 or x+=+1.25
Look at the graph of this equation:
graph%28400%2C400%2C-5%2C5%2C-10%2C5%2C2x%5E2-5x-3%29