A hall has 221 chairs arranged so that the number of rows is 4 more than the number of chairs in each row. Taking the number of rows as x gives x^2 - 4x - 221 = 0. How many rows are there?

Question

Accepted Answer

17. Each row holds x - 4 chairs, so x(x - 4) = 221 => x^2 - 4x - 221 = 0. D = 16 + 884 = 900, √D = 30. x = 4 ± 30/2 = 17 or -13. So 17 rows of 13 chairs, and 17 × 13 = 221.

A hall has 221 chairs arranged so that the number of rows is 4 more than
the number of chairs in each row. Taking the number of rows as $x$ gives
$x^{2} - 4 x - 221 = 0$ . How many rows are there?

Step-by-Step Solution

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More Class 10 The Quadratic Formula practice

A hall has 221 chairs arranged so that the number of rows is 4 more thanthe number of chairs in each row. Taking the number of rows as x givesx2−4x−221=0. How many rows are there?

Step-by-Step Solution

Master this chapter in 30 minutes a day.

More Class 10 The Quadratic Formula practice

A hall has 221 chairs arranged so that the number of rows is 4 more than
the number of chairs in each row. Taking the number of rows as $x$ gives
$x^{2} - 4 x - 221 = 0$ . How many rows are there?