what are the dimensions of the outer frame A (10+r)and(5+x) B(10-x) and (5-x) C(10+2x)and(5+2x) D(10-2x)and(5-2x)
Answers
Given : final area of the frame should be 54 sq m
Inner rectangle dimensions are l-10 b-5.
Outer is x meters from all sides
To Find : dimensions of the outer frame
Area of frame
Value of x
Perimeter of frame
Solution:
dimensions of the outer frame
10 + x + x and 5 + x + x
= 10 + 2x and 5 + 2x
Correct option is : c) (10 +2x) and (5 + 2x)
Area of frame = (10 +2x)(5 + 2x) = 50 + 20x + 10x + 4x²
= 4x² + 30x + 50
area of required final metal frame
= 4x² + 30x + 50 - ( 10 * 5)
= 4x² + 30x
4x² + 30x = 54
=> 2x² +15x = 27
=> 2x² +15x - 27 = 0
=> 2x² + 18x - 3x - 27 = 0
=> 2x(x + 9) - 3(x + 9) = 0
=> (2x - 3)(x + 9) = 0
=> x = 3/2 x = - 9 ( x can not be negative )
Hence x = 1.5 m
Perimeter of frame : 2(10 + 2x + 5 + 2x) = 30 + 8x
=30 + 8(1.5)
= 42 m
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