Question

Giovanni justifies whether the expression –4x – 8 is equivalent to Negative 2 (x + 1) minus 2 (x + 3) by letting x = 3 in both expressions. What is the value of each expression when x = 3?
3 and –20
4 and 4
–20 and –20
3 and 4

Answer 1

For x = 3:

-4x - 8 = -4(3) - 8 = -12 - 8 = -20

-2(x + 1) - 2(x + 3) = -2(3 + 1) - 2(3 + 3) = -2(4) - 2(6) = -8 - 12 = -20

So the value of each expression is -20 (third choice).