plzz answer above question..
chapter: second degree equations
Answers
Answer:
Let the length be "l" and breadth be "b".
given that, breadth is increased by 2 cm and length is reduced by 3 cm
Hence, breadth = (b + 2) cm
And length = (l - 3) cm.
Perimeter of the rectangle = 60 cm before changing the dimensions.
2(l + b) = 60 cm
l + b = 30 cm
l = 30 cm - b -- equation (1)
And also , after changing the dimensions of the rectangle the area = 210 cm²
(l - 3)(b + 2) = 210
Substitute "l" value here,
(30 - b - 3)(b + 2) = 210
(27 - b)(b + 2) = 210
27(b + 2) - b(b + 2) = 210
27b + 54 - b² - 2b = 210
- b² + 25b + 54 - 210 = 0
- b² + 25b - 156 = 0
-b² + 13b + 12b - 156 = 0
- b (b - 13) + 12(b - 13) = 0
(- b + 12)(b - 13) = 0
- b = - 12
b = 12
b - 13 = 0
b = 13.
Breadth of the first rectangle would be 12 or 13.
Substitute "b" value in equation (1)
l = 30 - b
l = 30 - 12 (or) 30 - 13
l = 18 or 17.
a) l = 30 - x.
b) length of the new rectangle = l - 3
= 18 - 3 (or) 17 - 3
= 15 or 14
c) l = 17 , 18
b = 13,12
Step-by-step explanation:
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