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secondary 4 | E Maths
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kim Yeon Jae
Kim Yeon Jae

secondary 4 chevron_right E Maths chevron_right Singapore

Please help thanku

Date Posted: 4 years ago
Views: 181
J
J
4 years ago
Original cost of each bulb
= $ 258/x

Number of bulbs sold = x - 3

Price each bulb was sold at
= $(258/x + 3)
= $(258 + 3x)/x

Amount of money collected from sale of the bulbs

= $(258+3x)/x × (x - 3)

= $(258 + 3x)(x - 3)/x

= $(258x - 774 + 3x² - 9x)/x

= $(3x² + 249x - 774)/x


Since amount collected also = $360,

(3x² + 249x - 774)/x = 360

3x² + 249x - 774 = 360x

3x² - 111x - 774 = 0

x² - 37x - 258 = 0

(x + 6)(x - 43) = 0

x = -6 or x = 43

(x = -6 is rejected as number of bulbs can't be negative)


So number of bulbs bought = 43


Selling price = $(258/x + 3)

= $(258/43 + 3)

= $(6 + 3)

= $9

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Eric Nicholas K
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kim Yeon Jae
Kim Yeon Jae
4 years ago
Thanku! :)