A wall paper , 312m long …
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Sia ? 4 years, 8 months ago
Length of wallpaper =312 m,
Breadth of wallpaper=25 cm =0.25 m
Area of wallpaper = 312 {tex}\times{/tex} 0.25 = 78.00 m2
Length of room = 7 m
Let height be x m, then it's breadth is 2x m
Surface area of four walls = 2 [lh + bh]
= 2 (7x + 2x2)
= 14x + 4x2
According to the question
Surface area of four walls= Area of wallpaper
4x2 + 14x = 78 {tex}\Rightarrow{/tex} 2x2 + 7x - 39 = 0
{tex}\Rightarrow{/tex} 2x2 + 13x - 6x - 39 = 0
{tex}\Rightarrow{/tex} x(2x + 13) - 3 (2x + 13) = 0
{tex}\Rightarrow{/tex}(x - 3) (2x + 13) = 0
{tex}\Rightarrow{/tex} x - 3 = 0 or 2x + 13 = 0
{tex}\Rightarrow{/tex} x = 3 or x = -{tex}\frac{13}{2}{/tex}(rejected) {tex}\Rightarrow{/tex} x = 3 m
Hence, height of the room is 3 m.
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