Finding Constants for Quadratic Equations

In summary, quadratic equations are algebraic expressions that involve a variable raised to the second power and are written in the form of ax^2 + bx + c = 0. To find the constants for a quadratic equation, you can use the formula y = ax^2 + bx + c and substitute known values for x and y. The constant "a" in a quadratic equation determines the shape and steepness of the parabola. The constants for a quadratic equation can be irrational numbers, and the quadratic formula is often used to find solutions and solve for the constants.
  • #1
anemone
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Find constants $P,\,Q,\,R,\,S, a,\,b$ such that

$P(x-a)^2+Q(x-b)^2=5x^2+8x+14$

$R(x-a)^2+S(x-b)^2=x^2+10x+7$
 
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  • #2
anemone said:
Find constants $P,\,Q,\,R,\,S, a,\,b$ such that

$P(x-a)^2+Q(x-b)^2=5x^2+8x+14$

$R(x-a)^2+S(x-b)^2=x^2+10x+7$
compare both sides we get:
$P+Q=5---(1)$
$aP+bQ=-4---(2)$
$a^2P+b^2Q=14---(3)$
$R+S=1---(4)$
$aR+bS=-5---(5)$
$a^2R+b^2S=7---(6)$
from (1)(2)(3) we get :
$-b=\dfrac {14+4a}{5a+4}---(7)$
from (4)(5)(6) we get :
$-b=\dfrac {7+5a}{a+5}--(8)$
from (7)(8) we get :
$a=-2,1$
the rest is easy ,and the solutions will be:
$(a,b,P,Q,R,S)=(-2,1,3,2,2,-1)$
or:
$(a,b,P,Q,R,S)=(1,-2,2,3-1,2)$
 
  • #3
Thanks for participating, Albert and your answer is correct!:)
 

What are quadratic equations?

Quadratic equations are algebraic expressions that involve a variable raised to the second power. They are written in the form of ax^2 + bx + c = 0, where a, b, and c are constants and x is the variable. These equations often have two solutions.

How do I find the constants for a quadratic equation?

To find the constants for a quadratic equation, you need to know at least two points on the parabola represented by the equation. You can then use the formula y = ax^2 + bx + c and substitute the known values for x and y to create a system of equations. Solving this system will give you the values for a, b, and c.

What is the significance of the constant "a" in a quadratic equation?

The constant "a" in a quadratic equation determines the shape of the parabola. If a is positive, the parabola opens upwards, and if a is negative, the parabola opens downwards. The value of a also affects the steepness of the curve.

Can the constants for a quadratic equation ever be irrational numbers?

Yes, the constants for a quadratic equation can be irrational numbers. For example, the equation x^2 + √2x + √3 = 0 has the constants a = 1, b = √2, and c = √3, all of which are irrational numbers.

What is the role of the quadratic formula in finding the constants for a quadratic equation?

The quadratic formula, which is (-b ± √(b^2 - 4ac))/2a, is used to find the solutions to a quadratic equation. It can also be rearranged to solve for the constants a, b, and c. This formula is often used when the constants for a quadratic equation cannot be easily determined by other methods.

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