Question

Solve the equation by completing the square. Round to the nearest hundredth if necessary.
x^2 - 4x = 5
A) 11,-7
B) 1.73,-1.73
C) 5,-1
D) 1,3

Answer 1

Answer:

C) 5,-1

Step-by-step explanation:

Given equation is $\[x^{2}-4x=5\]$

Expressing the equation equivalently,

$\[x^{2}-4x-5=0\]$

$\[=> x^{2}-5x+x-5=0\]$

$\[=> x*(x-5)+1*(x-5)=0\]$

$\[=> (x-5)*(x+1)=0\]$

Hence the solutions of this equation can be represented as x-5=0 and x+1=0

In other words, x=5 or x=-1

Among the given options, option C is the correct one.

Answer 2

Answer:

C

Step-by-step explanation:

Step 1, the coefficient of x is -4

Step 2, divide it by 2= -2

Step 3, square your answer and add to both sides

Square of -2 is 4, and  we add to both sides of the equation to give,

x^2 - 4x + 4 = 5 +4

X^2 +4 = 9

(x +2)^2 = 9

take the sqrt of both sides, we have

X +2 =  sqrt (9)

X = 2(+ or -) Sqrt (9)

X = 2+ Sqrt (9), 2-sqrt (9)

X = 2+3, 2-3

X= 5, -1