9514 1404 393
Answer:
10. x = 4
11. x = -5
Explanation:
10. Use the perimeter formula. Collect terms, subtract* the constant, divide by the coefficient of the variable.
P = 2(L+W)
42 = 2(5x +(x-3))
21 = 6x -3 . . . . . . divide by 2, collect terms
24 = 6x . . . . . . . . add 3
4 = x . . . . . . . . . . divide by 6
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11. Collect terms, subtract the constant, divide by the coefficient of the variable.
-8x -3(2x +1) = 67
-8x -6x -3 = 67 . . eliminate parentheses
-14x -3 = 67 . . . . . collect terms
-14x = 70 . . . . . . . add 3
x = -5 . . . . . . . . . . divide by -14
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* "Subtract" and "add the opposite" are the same mathematical operation. In both these problems, the constant we want to get rid of is -3, so we add 3 (the opposite of -3). Of course, that operation is done to both sides of the equation.