Math, asked by anujgawali92, 10 months ago

x( x +2) =8 solve completing the square​


HarshaVardhan05: x=2

Answers

Answered by mysticd
6
Solution:

x(x+2)=8

=> x²+2x = 8

=> x²+2*x*1 = 8

=> x²+2*x*1+1² = 8+1²

/* adding 1 both sides */

=> (x+1)² = 9

=> (x+1) = ±√9

=> x+1 = ± 3

=> x = -1±3

Therefore,

x = -1+3 or x = -1-3

=> x = 2 or x = -4

••••

Anonymous: well I think last step should be
Anonymous: -1 - 3 and -1 + 3
Anonymous: please correct it
mysticd: Thank you.
Anonymous: ^_^
Answered by Anonymous
13

Answer :-

◾Here we have the question

x(x+2) = 8

▪️we have to solve it via multiplication

◾By multiplication of LHS we get

 \sf{x^2 + 2x = 8}

◾Now subtracting 8 from both LHS and RHS

 \sf{ x^2 + 2x - 8 = 8 - 8}

\sf{ x^2 + 2x - 8 = 0}

⏩So now we have got a quadratic equation , now solving it via Splitting middle term :-

\sf{x^2 + 4x - 2x - 8 = 0}

\sf{ x(x + 4) -2(x + 4) = 0}

\sf{ (x+4)(x-2) = 0}

⏩So we get

x = -4

or

x = 2

♦ So Answer

\bold{x = 2 \:or \:-4 }


mysticd: This is not completing square method.
mysticd: what you did is factorisation method.
Anonymous: oops ... let me do it again !!
Anonymous: but it will match your answer if I edit it ........ :(
Anonymous: it's not allowed to me
mysticd: naturally .
mysticd: :)
mysticd: do you want to explain it thoroughly.
Anonymous: ??
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