What is the value of the rational expression x-2x2-3/4x2-12 when x = 3?
-1/4
0
1/4
undefined

(-135)/4

Step-by-step explanation:

Evaluate -(3 x^2)/4 - 2 x^2 + x - 12 where x = 3:

-(3 x^2)/4 - 2 x^2 + x - 12 = 3 - 2×3^2 - 3/4×3^2 - 12

3^2 = 9:

3 - 29 - 3/4×3^2 - 12

3^2 = 9:

3 - 2×9 - 3/4×9 - 12

-2×9 = -18:

3 + -18 - 3/4×9 - 12

-3×9 = -27:

3 - 18 + (-27)/4 - 12

Put 3 - 18 - 27/4 - 12 over the common denominator 4. 3 - 18 - 27/4 - 12 = (4×3)/4 + (4 (-18))/4 - 27/4 + (4 (-12))/4:

(4×3)/4 - (18×4)/4 - 27/4 - (12×4)/4

4×3 = 12:

12/4 - (18×4)/4 - 27/4 - (12×4)/4

4 (-18) = -72:

12/4 + (-72)/4 - 27/4 - (12×4)/4

4 (-12) = -48:

12/4 - 72/4 - 27/4 + (-48)/4

12/4 - 72/4 - 27/4 - 48/4 = (12 - 72 - 27 - 48)/4:

(12 - 72 - 27 - 48)/4

12 - 72 - 27 - 48 = 12 - (72 + 27 + 48):

(12 - (72 + 27 + 48))/4

| 1 |  

| 7 | 2

| 4 | 8

+ | 2 | 7

1 | 4 | 7:

(12 - 147)/4

12 - 147 = -(147 - 12):

(-(147 - 12))/4

| 1 | 4 | 7

- | | 1 | 2

| 1 | 3 | 5:

(-135)/4

99

step-by-step explanation:

answer: i think it is (1,-2)