If x^2 - 16 > 0, which of the following must be true?

1 answer:

5 0

The left hand side of the equation is a difference of two squares and may be factored out as follows,
(x - 4)(x + 4) > 0
They may be individually taken as,
x - 4 > 0 ; x > 4
x + 4 > 0 ; x < -4
Thus, the answer to this item is letter A.

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arman needs 4 1/2 inches of cable to make A,3 3/4 inches to make B, and 5 1/8 inches to make C. He used a 12 inch piece of cable

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4 1/2 + 3 3/4 = 4 2/4 + 3 3/4 = 7 5/4 = 8 1/4...what he needs for A and B

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Solve (x + 1)2 – 4(x + 1) + 2 = 0 using substitution.

solniwko [45]

For this case we have to:

Let $u = x + 1$

So:

$u ^ 2-4u + 2 = 0$

We have the solution will be given by:

$u = \frac {-b \pm \sqrt {b ^ 2-4 (a) (c)}} {2 (a)}$

Where:

$a = 1\\b = -4\\c = 2$

Substituting:

$u = \frac {- (- 4) \pm \sqrt {(- 4) ^ 2-4 (1) (2)}} {2 (1)}\\u = \frac {4 \pm \sqrt {16-8}} {2}\\u = \frac {4 \pm \sqrt {8}} {2}\\u = \frac {4 \pm \sqrt {2 ^ 2 * 2}} {2}\\u = \frac {4 \pm2 \sqrt {2}} {2}$