Question

Solve x2 – 8x = 20 by completing the square. Which is the solution set of the equation? {–22, 14} {–14, 22} {–10, 2} {–2, 10}

Answer 1

–2, 10 chicken give me tendies  

Answer 2

Answer: D is the right answer. The solution set of the given equation={-2,10}.

Step-by-step explanation:

Given equation:
`x^2-8x=20`

The standard perfect square trinomial equation is
`x^2+2ax+a^2=(x+a)^2`

On comparing this with the left side of the given equation ,we get 2a=-8

⇒a= -4 and
`a^2=16`

Now to make given equation perfect square add 16 on the both sides, we get
`x^2-8x+16=20+16\\\Rightarrow(x-4)^2=36`

Taking square root on both the sides we get,

`x-4=-6\ or\ x-4=6`

add 4 on both sides, we get

⇒x= -6+4 or x=6+4

⇒x=-2 or x=10

Therefore, the solution set of the given equation={-2,10}.

Thus D is the right answer.