Assignment: Relating Solutions and Roots

Fill in the missing steps for the derivation of the quadratic formula using the choices below.

[tex]$A: x+\frac{b}{2a}=\frac{\pm \sqrt{b^2-4ac}}{2a}$[/tex]
[tex]$B: x^2+\frac{b}{a}x=\frac{-c}{a}$[/tex]
[tex]$C: x=\frac{-b \pm \sqrt{b^2-4ac}}{2a}$[/tex]
[tex]$D: \left(x+\frac{b}{2a}\right)^2=\frac{-4ac+b^2}{4a^2}$[/tex]

Step 1: [tex]$ax^2+bx+c=0$[/tex]
Step 2: [tex]$ax^2+bx=-c$[/tex]
Step 3: [tex]$\square$[/tex]
Step 4: [tex]$x^2+\frac{b}{a}x+\frac{b^2}{4a^2}=\frac{-c}{a}+\frac{b^2}{4a^2}$[/tex]
Step 5: [tex]$\square$[/tex]
Step 6: [tex]$\square$[/tex]
Step 7: [tex]$x=-\frac{b}{2a} \pm \frac{\sqrt{b^2-4ac}}{2a}$[/tex]
Step 8: [tex]$\square$[/tex]



Answer :

Let's tackle the derivation of the quadratic formula step-by-step and fill in the missing steps with the appropriate given choices:

Step 1: [tex]\( a x^2 + b x + c = 0 \)[/tex]

This is the general form of the quadratic equation.

Step 2: [tex]\( a x^2 + b x = -c \)[/tex]

We move the constant term [tex]\( c \)[/tex] to the other side of the equation.

Step 3: [tex]\( B: x^2 + \frac{b}{a} x = \frac{-c}{a} \)[/tex]

We divide every term by [tex]\( a \)[/tex] to normalize the coefficient of [tex]\( x^2 \)[/tex] to 1.

Step 4: [tex]\( x^2 + \frac{b}{a} x + \frac{b^2}{4 a^2} = \frac{-c}{a} + \frac{b^2}{4 a^2} \)[/tex]

We add [tex]\(\frac{b^2}{4 a^2}\)[/tex] to both sides of the equation to complete the square on the left side.

Step 5: [tex]\( D: \left(x + \frac{b}{2 a} \right)^2 = \frac{b^2}{4 a^2} - \frac{4 a c}{4 a^2} \)[/tex]

We complete the square on the left and combine the fractions on the right.

Step 6: [tex]\( (x + \frac{b}{2 a})^2 = \frac{b^2 - 4 a c}{4 a^2} \)[/tex]

We simplify the right-hand side.

Step 7: [tex]\( x = -\frac{b}{2 a} \pm \frac{\sqrt{b^2 - 4 a c}}{2 a} \)[/tex]

Taking the square root of both sides, we solve for [tex]\(x\)[/tex].

Step 8: [tex]\( C: x = \frac{-b \pm \sqrt{b^2 - 4 a c}}{2 a} \)[/tex]

This is the simplified form of the quadratic formula.

Therefore, the filled steps are:

1. [tex]\( a x^2 + b x + c = 0 \)[/tex]
2. [tex]\( a x^2 + b x = -c \)[/tex]
3. [tex]\( B: x^2 + \frac{b}{a} x = \frac{-c}{a} \)[/tex]
4. [tex]\( x^2 + \frac{b}{a} x + \frac{b^2}{4 a^2} = \frac{-c}{a} + \frac{b^2}{4 a^2} \)[/tex]
5. [tex]\( D: \left(x + \frac{b}{2 a} \right)^2 = \frac{b^2}{4 a^2} - \frac{4 a c}{4 a^2} \)[/tex]
6. [tex]\( (x + \frac{b}{2 a})^2 = \frac{b^2 - 4 a c}{4 a^2} \)[/tex]
7. [tex]\( x = -\frac{b}{2 a} \pm \frac{\sqrt{b^2 - 4 a c}}{2 a} \)[/tex]
8. [tex]\( C: x = \frac{-b \pm \sqrt{b^2 - 4 a c}}{2 a} \)[/tex]

This completes the derivation of the quadratic formula with the correctly filled steps.