the sum of four times a number and eight is between zero and twelve. find the range of numbers. write a compound inequality.
1 answer:
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Let, the length be l and breadth be b.
So, 2(l + b) = 26
Or, l + b = 13
Or, l = 13 - b
So, we may write like this,
Area = l * b
Or, l * b > 30
Or, l (13 - l) > 30
Or, 13l - l^2 > 30
Or, l^2 - 13l + 30 > 0
Or, l^2 - 3l - 10l + 30 > 0
Or, l(l - 3) - 10(l - 3) > 0
Or, (l - 3)(l - 7) > 0
Or, l - 7 > 0
Or, l > 7.
Now, putting the value of l,
We get, l * b > 30
Or, 7 * b > 30
Or, b > 30/7
➡️ Therefore, we get,
Length > 7
Breadth > 30/7
That's it..