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From the sum of 3a + 4b, - 5a + 2b - 9 and 2a - 5b + 7) subtract (-8a + 7b + 9). Find the value of the result for a = 1 and b=-1. |
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Answer» n:★ First we have to find the sum of 3a + 4b, - 5a + 2b - 9 and 2A - 5b + 7.→ Adding the terms:= 3a + 4b - 5a + 2b - 9 + 2a - 5b + 7→ Arranging the like terms together:= 3a - 5a + 2a + 4b + 2b - 5b - 9 + 7→ Applying the required operations on the like terms:= 5a - 5a + 6B - 5b - 2→ Cancelling like terms with opposite signs:= 6b - 5b - 2= b - 2★ Now, we have to subtract -8a + 7b + 9 from it.= b - 2 - (-8a + 7b + 9)→ Opening the brackets:= b - 2 + 8a - 7b - 9→ Arranging the like terms together:= b - 7b - 2 - 9 + 8a= -6b - 11 + 8a★ Now PUTTING the value of a as 1 and b as -1 in the expression:= (-6 x 1) - 11 + (8 x -1)= -6 - 11 - 8= -25Hence the required correct answer is -25 when we put the value of a as 1 and b as -1 to the expression -6b - 11 + 8a. |
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