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3 years ago

X^2 -6x - 15 = 0 complete the square

Mathematics

2 answers:

Leviafan [203]3 years ago

6 0

Answer:

(x - 3)^2 = 24.

Step-by-step explanation:

x^2 -6x - 15 = 0

(x - 3)^2 - 9 - 15 = 0

(x - 3^2 -24 = 0

(x - 3)^2 = 24.

blondinia [14]3 years ago

5 0

Recalling that

$(x-a)^2=x^2-2ax+a^2$

Let's compare the middle term:

$-6x = -2ax \iff a=3$

So, we want to complete

$(x-3)^2 = x^2-6x+9$

Which differs from $x^2-6x-15$ by 24. So, if we add 24 to both sides, we have

$x^2-6x-15=0 \iff x^2-6x+9=24 \iff (x-3)^2=24$

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