(45,0), (0, 1.39), and (18, 3.2) Use those to find the equation of the quadratic.
x=ax^2+bx+c

Question

(45,0), (0, 1.39), and (18, 3.2)  Use those to find the equation of the quadratic.
x=ax^2+bx+c

mathmale · Answer

This is quite an interesting problem (at least to me).
Each of the 3 points contains info on x and y:  In (45,0), x=45 and y=0.
Substitute those values into the quadratic y=ax^2+bx+c.
You'll come up with an equation in a, b and c.
Do the same thing for the other two points.
You'll end up with 3 equations in a, b and c.
Your job is to solve this system of linear equations for a, b and c.
Then write out the original quadratic, substituting your values of a, b and c.

anonymous · Answer

Whats The Original Equation Look Like?

mathmale · Answer

The "original equation" is your x=ax^2+bx+c.  all you need to change here is that initial x:  You meant y=ax^2+bx+c.

anonymous · Answer

Oh Okay Thank You And May I Ask If These Look Alright:
2025a+45b+c
c=1.39
3.2=324a+18b+c

mathmale · Answer

@LannaBoo24:  The first expression you've typed in is not an equation.  Can you fix this, so that you DO have an equation there?

anonymous · Answer

Un Square It?

mathmale · Answer

Notice that you don't have an ' = ' sign in the first expression you've typed in.  That means you have an expression, not an equation.  What you are trying to say in writing this equation is that "when x=45, y=0."  Can you now fix the first expression (make it an equation)?

mathmale · Answer

2025a+45b+c=0.
Now you have 3 equations in the three unknowns, a, b and c.
Please solve for a, b and c.

anonymous · Answer

C=1.39 So I Can Just Put That Into The Other Two Equations Like This:
2025a+45b+1.39=0
324a+18b+1.39=3.2  Right?

mathmale · Answer

Sure!  That's one of the faster ways of solving this problem.  Now you need only find the values of a and b.

anonymous · Answer

Okkie Dokkie c: Well  On The 2nd Equation That Has To Be Equal To 0 Also Or Is It Okay Like It Is?

mathmale · Answer

Actually, your second equation is 0a + 0b +1c = 1.39, so your c=1.39 is correct.

anonymous · Answer

Opps. I Meant In The 324a+18b+1.39=3.2 Sorry.

mathmale · Answer

That you can find your own mistakes shows that you understand a great deal of what is happening here.  :)

mathmale · Answer

You're on the right track.
I need to get off the Internet now, unfortunately.  Good luck!!

anonymous · Answer

Thank You c: