Respuesta :

Step 1:
x² + 4x = 192

Step 2:
Take x common:
x ( x + 4) = 192

Length is x and width is x+4

Step 3:

x² + 4x - 192 = 0

Step 4:

x² + 16x - 12x - 192 = 0
x(x+16) - 12(x+16) = 0
(x-12)(x+16) = 0

⇒ x=12, x=-16

Because the length can't be -16, the length is 12.
sqdancefan
Step 2: {4, x+4}
Factoring x²+4x, you get x(x+4). If you call the length x, then the width is the other factor, x+4.

Step 4: {16}
You know this two ways. -192/-12 = 16, and 4 -(-12) = 16, where 4 is the coefficient of x in step 3.

Last line: {-16, 16}
The values of x that make the factors zero are -16 and 12. Since these are supposed to represent lengths, an appropriate answer cannot be negative (-16). The width is x+4 = 12+4 = 16.

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