3 years ago

Kaylee is building a rectangular enclosure with an area of 90 square yards. She

Mathematics

2 answers:

alexgriva [62]3 years ago

6 0

x^2 + 6x = 90

x^2 + 6x + 9 = 90 + 9

(x + 3)(x + 3) = 99

(x + 3)^2 = 99

Answer: B

pshichka [43]3 years ago

4 0

The answer is B have a great rest of your night or day :)

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Ed is planning daily walking workouts on the same distance of 12 km in the morning and in the evening. Usually he is walking at

dezoksy [38]

Answer:

5 km/h

Step-by-step explanation:

Let x km/h be Ed's rate in the evening, then x+1 km/h is his rate in the morning. It takes him

$\dfrac{12}{x+1}$ hours in the morning to pass 12 km;
$\dfrac{12}{x}$ hours in the evening to pass 12 km.

In total, it takes him 5 hours 24 minutes ( $5\dfrac{24}{60}=5.4$ hours), then

$\dfrac{12}{x+1}+\dfrac{12}{x}=5.4.$

Solve this equation:

$\dfrac{12x+12(x+1)}{(x+1)x}=5.4,\\ \\12x+12x+12=5.4x^2+5.4x,\\ \\5.4x^2 -18.6x-12=0,\\ \\54x^2-186x-120=0,\\ \\9x^2 -31x-20=0,\\ \\D=(-31)^2-4\cdot 9\cdot (-20)=1,681=41^2,\\ \\x_{1,2}=\dfrac{-(-31)\pm\sqrt{41^2}}{2\cdot 9}=\dfrac{31\pm41}{18}=-\dfrac{5}{9},\ 4\ km/h.$