Brainliest rewarded to correct answer mickey simplified the expression below. he then checked his work by substituting 4 for x. he noticed his two values were not equal. what was mickey’s error when simplifying? expression: 2x^2 - 4x - 9 - x^2 + 2x + 3 simplified expression: x^2 - 6x - 6 answer choices: mickey should have added –4 and 2 when combining the coefficients of the x terms. mickey should have added 2 and 1 when combining the x^2 terms. mickey should have added 9 and 3 when combining the constant terms. mickey should have added –4 and –1 when combining the x terms.

Mickey should have added –4 and 2 when combining the coefficients of the x terms.

Step-by-step explanation:

Mickey simplified the expression below. He then checked his work by substituting 4 for x. He noticed his two values were not equal

Expression: 2x^2 - 4x - 9 - x^2 + 2x + 3

Simplified expression: x^2 - 6x - 6

2x^2- x^2 - 4x + 2x - 9  + 3

x^2 -2x -6

-4x +2x = -2x (both have different sign so we subtract)

Mickey should have added –4 and 2 when combining the coefficients of the x terms.

d. millimeters per hour.

step-by-step explanation:

we are given that,

carlo used a rain gauge to measure the amount of water his lawn is receiving from the sprinklers.

since, according to the options, we see that,

water cannot be measured by 'miles per hour', 'meters per second' and 'grams per seconds'.

we get that, the water can be measured by 'millimeters per hour'.

hence, the appropriate rate for describing the amount of water is 'millimeters per hour'.