Complete the square for 2x2 – 4x = 14? A. (2x – 2)2 = 30 B. (2x – 1)2 = 15 C. (x – 1)2 = 8 D. (x + 1)2 = 8

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Complete the square for 2x2 – 4x = 14? A. (2x – 2)2 = 30 B. (2x – 1)2 = 15 C. (x – 1)2 = 8 D. (x + 1)2 = 8

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Answer 1 · 2018-04-16T15:40:15

C.

Explanation:

$2 x^{2} - 4 x = 14$ $2x^2-4x=14$
Firstly, divide the equation by 2 so that coeffecient of $x^{2}$ $x^2$ =1
$x^{2} - 2 x = 7$ $x^2-2x=7$
Now, add the square of half the coeffecient of x both sides i.e.
$x^{2} - 2 x + {(\frac{2}{2})}^{2} = 7 + {(\frac{2}{2})}^{2}$ $x^2-2x+(2/2)^2=7+(2/2)^2$
$x^{2} - 2 x + 1 = 8$ $x^2-2x+1=8$
as, $x^{2} - 2 x = 8$ $x^2-2x=8$ is the identity of ${(x - 1)}^{2}$ $(x-1)^2$
so, ${(x - 1)}^{2} = 8$ $(x-1)^2=8$
so correct answer is C.

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Complete the square for 2x2 – 4x = 14? A. (2x – 2)2 = 30 B. (2x – 1)2 = 15 C. (x – 1)2 = 8 D. (x + 1)2 = 8

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