Respuesta :
Answer:
step 1: [tex]ax^2[/tex]+bx+c=0
step 2:[tex]ax^2+bx=-c[/tex]
step 3: [tex]x^2+\frac{b}{a}x=\frac{-c}{a}[/tex]
step 4:[tex]x^2+(\frac{b}{2a})^{2} =\frac{b}{2a}) ^{2} \frac{-c}{a}[/tex]
step 5: [tex](x+\frac{b}{2a} )^{2} =\frac{b^2-4ac}{4a^2}[/tex]
step 6:[tex]x=\sqrt{\frac{b^2-4ac}{4a^2} }[/tex]
step 7: [tex]x=\sqrt{\frac{b^2-4ac}{2a}[/tex]
Step-by-step explanation:
from step 6 there should be a plus and minus sign before the square root.
The given expression for x is [tex]x = { \frac{-b\pm\sqrt{b^2-4ac} }{2a}} \\[/tex]
Given the quadratic expression [tex]ax^2 + bx+ c = 0[/tex]
We are to make x the subject of the formula using the completing the square method
Step 1: Given the equation [tex]ax^2 + bx+ c = 0[/tex]
Step 2: Subtract c from both sides
[tex]ax^2+bx+c-c = 0-c\\ax^2+bx = -c[/tex]
Step 3: Divide through by a:
[tex]\frac{ax^2}{a} + \frac{b}{a} x= \frac{-c}{a} \\x^2 +\frac{b}{a} x=\frac{-c}{a} \\[/tex]
step 4: Add the square of half of the coefficient of x to both sides:
[tex]\\x^2 +\frac{b}{a} x + (\frac{b}{2a} )^2=\frac{-c}{a} + (\frac{b}{2a} )^2\\ \\x^2 +\frac{b}{a} x + \frac{b^2}{4a^2} =\frac{-c}{a} + \frac{b^2}{4a^2} \\(x+\frac{b}{2a} )^2 = \frac{-c}{a} + \frac{b^2}{4a^2} \\[/tex]
Step 5: Find the LCM
[tex](x+\frac{b}{2a} )^2 = \frac{-4ac+b^2}{4a^2} \\(x+\frac{b}{2a} )^2 = \frac{b^2-4ac}{4a^2}[/tex]
Step 6: Square root both sides:
[tex]\sqrt{(x+\frac{b}{2a} )^2} =\sqrt{ \frac{b^2-4ac}{4a^2}} \\x+\frac{b}{2a} =\pm\sqrt{ \frac{b^2-4ac}{4a^2}} \\x = -\frac{b}{2a} \pm{ \frac{\sqrt{b^2-4ac} }{2a}} \\[/tex]
Step 7: Simplify to get the value of x
[tex]x = { \frac{-b\pm\sqrt{b^2-4ac} }{2a}} \\[/tex]
This given the required value of x
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