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.
Answers
Answer:-9
Step-by-step explanation: first of all put values you can see that multiplying 1 with all the terms will be the same term again so put values like that you will get 3 + 4 - 5+2-9 + ( 2 - 5 + 7 ) - ( -8 + 7 + 9 )
you have to then open bracket's and then add
you will get -9 as answer
Solution:
★ 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
= -25
Hence 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.