19)
Evaluate 2 x^2-3 x^3 where x = -1:
2 x^2-3 x^3 = -3×(-1)^3+2×(-1)^2
(-1)^3 = -1:
2×(-1)^2-3-1
(-1)^2 = 1:
-(-3)+2
-3 (-1) = 3:
3+2
3+2 = 5:
Answer: 5
20)
-3x^3 + 2x^2=?, where x=1/2
-3.(1/2)^3 + 2.(1/2)^2 =
[-3 x 1/8] + [2 x 1/4] =
[-3/8] + [ 1/2] =1/8
