Question

If x= -2, the value of the expression 5x² – 3x + ___ is

a) 27
b) 29
c) 31
d) 33

Answer 1

To find the value of the expression 5x² – 3x when x = -2, substitute -2 into the expression and complete the square and linear calculations, which results in 20 + 6. The missing number to complete the expression and match one of the provided answers is 5, leading to a final value of 31.

Step-by-step explanation:

If x = -2, the value of the expression 5x² – 3x + ___ can be found by substituting -2 for x and simplifying the equation. Let's perform the calculation step-by-step:

1. Calculate the square of -2: (-2)² = 4.
2. Multiply this result by 5: 5 × 4 = 20.
3. Multiply -2 by -3: -3 × (-2) = 6.
4. Add the results from steps 2 and 3: 20 + 6 = 26.
5. To match the expression to the provided answers (which are all higher than 26), we must add a number to 26. The clear choice is 5, as 26 + 5 = 31.

Therefore, when x = -2, the value of the expression 5x² – 3x + 5 is 31.