# How do you use synthetic substitution to find x=3 for #f(x)=-3x^3+7x^2-4x+8#?

##### 2 Answers

-22

#### Explanation:

f(3) would be

=-81 +63 -12+8

=-22

#### Explanation:

Refer to the details below the diagram for an explanation of each step:

Write substitution value (in this case

leave space for another line of numbers under this, then draw a vertical line.

Copy the first (highest order) coefficient to below the line.

Multiply the substitution value and the left-most value under the line and write the product under the second coefficient.

Add the two values in the second coefficient position and write the sum below the line.

Multiply the substitution value and the second value under the line and write the product under the third coefficient.

Add the two values in the third coefficient position and write the sum below the line.

Multiply the substitution value and the third value under the line and write the product under the fourth coefficient.

Add the two values in the fourth coefficient position and write the sum below the line.

This last sum is the value of the expression at the substitution value.