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spin [16.1K]
3 years ago
13

Solve x2-14x+21=0 by completing the square

Mathematics
1 answer:
ankoles [38]3 years ago
4 0
x^2-14x+21=0\\\\x^2-2x\cdot7+7^2-7^2+21=0\\\\(x-7)^2-49+21=0\\\\(x-7)^2-28=0\\\\(x-7)^2=28\iff x-7=-\sqrt{28}\ \vee\ x-7=\sqrt{28}\\\\x=7-\sqrt{4\cdot7}\ \vee\ x=7+\sqrt{4\cdot7}\\\\x=7-2\sqrt7\ \vee\ x=7+2\sqrt7
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The Webster family is planning a barbecue for one hundred people. The Webster family needs one plastic plate for each person at
Pachacha [2.7K]

The question is incomplete:

The Webster family is planning a barbecue for one hundred people. The Webster family needs one plastic plate for each person at the barbecue. The Stop and Shop store and Market Place Store both sell plastic plates in packages of fifteen for five dollars and ninety-nine cents per package. How many packages of plastic plates does the Webster family need to buy? What is the cost of plates for the barbecue?

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To calculate amount of packages that the Webster family need to buy, you have to divide the amount of people by the number of plates in each package:

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