Question

please help..... explain in steps

Use the technique of completing the square to transform the quadratic equation into the form (x + c)2 = a.

5x2 + 20x - 120 = 0

answer:
(x + 2)2 = 28 (x + 5)2 = -21
(x + 2)2 = -28 (x + 4)2 = 21

Answer 1

If your original quadratic is \[ ax^2+bx+c=0\], then you first divide through by \(a\) to get rid of the leading coefficient. Then you want to add and subtract the term: \(\large \left(\frac{b}{2} \right)^2\)

\(5x^2+20x-120 =0 \), divide by 5
\(x^2+4x-24 = 0\)

Now add and subtract \(\large \left( \frac{4}{2}\right)^2=4\)
\[ \underbrace{x^2+4x+ 4}-4-24=0\\
\underbrace{(x+2)^2}-28=0\\
(x+2)^2=28\]

Answer 2

thanx :)

Answer 3

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