Question 176075
-2[2z-(5z+2)] = 2 + (2z+7)
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remove the brackets, remembering the rule of signs 
-2(2z) - (-2)(5z+2) = 2 + 2z + 7
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Minus a minus is plus
-4z + 2(5z + 2) = 2z + 9
:
-4z + 10z + 4 = 2z + 9
:
6z + 4 = 2z + 9
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6z - 2z = 9 - 4
:
4z = 5
z = {{{5/4}}}
z = 1.25
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Check solution in original equation, substitute 1.25 for z
-2[2(1.25) - (5(1.25) + 2)] = 2 + (2(1.25) + 7)
:
-2[2.5 - (6.25 + 2)] = 2 + (2.5 + 7)
:
-2(2.5 - 8.25) = 2 + 2.5 + 7
:
-2(-5.75) = 11.5
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+11.5 = 11.5; confirms our solution
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