SOLUTION: Hi I'm having trouble with the following questions, i would be grateful if you could help me out, they are questions that i came across while revising for a test i've tried my ha

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Hi I'm having trouble with the following questions, i would be grateful if you could help me out, they are questions that i came across while revising for a test i've tried my ha      Log On


   

Question 12589: Hi
I'm having trouble with the following questions, i would be grateful if you could help me out, they are questions that i came across while revising for a test i've tried my hardest to solve them but i cant work it out (Can you please provide me with thier answers, i think i can figure them out if i have an answer to work from.)
The questions are:
1.What is the axis of symmetry for the following parabola?
y = x² + 4x
2.What is the axis of symmetry for the following parabola?
y = x(4 - x)
3.What is the vertex of the following parabola?
y = 4x² - 8
4.Factorise the following quadratic expression
2x² - 3x - 2
I've tried but i cant solve those answers
Thnkyou very much
Yours sincerly
Vinny
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
1) The axis of symmetry is given by:
x+=+-b%2F2a
x+=+%28-4%29%2F2
x+=+-2 This is the axis of symmetry.
2)
y+=+x%284-x%29
y+=+-x%5E2+%2B+4x
The axis of symmetry:
x+=+%28-4%29%2F-2
x+=+2 This is the axis of symmetry.
3) The x-coordinate of the vertex is given by:
x+=+-b%2F2a The same as the axis of symmetry.
x+=+0%2F2%284%29 The coefficient of the x-term (that's b)is 0.
x+=+0
The y-coordinate is found by substituting x = 0 into the quadratic equation and solving for y.
y+=+4%280%29%5E2+-+8
y+=+-8
The vertex is at: (0, -8)
4) Factorise (UK?): 2x%5E2+-+3x+-+2 = %282x+%2B+1%29%28x+-+2%29