Question

What should be added to (16a + 15b - 2c - 9d +7) to get (9a - 2b - c + 6d + 2)?

• A. -7a - 17b + c + 15d - 5
• B. -7a - 7b + 3c + 15d - 5
• C. -7a - 17b + 2c + 15d - 5
• D. -7a - 17b + c + 5d - 5

Answer 1

The correct option is A -7a - 17b + c + 15d - 5

Let 'y' be the term to be added to (16a + 15b - 2c - 9d +7) to get (9a - 2b - c + 6d + 2)
$\Rightarrow$ (16a + 15b - 2c - 9d +7) + y = (9a - 2b - c + 6d + 2)
Subtracting (16a + 15b - 2c - 9d +7) from (9a - 2b - c + 6d + 2), we get
y = (9a - 2b - c + 6d + 2) - (16a + 15b - 2c - 9d +7)
Grouping the like terms together, we get
y = (9a - 16a) + (-2b - 15b) + (-c + 2c) + (6d + 9d) + (2 - 7),
y = -7a - 17b + c + 15d - 5.