The polynomials x cube 3 x square - 3 and 2 x cube minus 5x a leav...
Problem:
The polynomials x cube 3 x square - 3 and 2 x cube minus 5x a leave the same remainder in each case when divided by x minus 4 find the value of.
Solution:
To find the value of x, we need to use the remainder theorem. The remainder theorem states that if a polynomial P(x) is divided by x - a, then the remainder is P(a).
Step 1:
We need to find the remainder when x cube + 3x square - 3 is divided by x - 4. To do this, we can use long division or synthetic division.
Long division method:
__________
x - 4 | x³ + 3x² - 3
x³ - 4x²
--------
7x² - 3
7x² - 28x
--------
28x - 3
28x - 112
--------
109
Therefore, the remainder is 109 when x cube + 3x square - 3 is divided by x - 4.
Synthetic division method:
4 | 1 3 -3
4 28 100
--------
1 7 25
Therefore, the remainder is 25 when x cube + 3x square - 3 is divided by x - 4.
Step 2:
We need to find the value of k such that 2x³ - 5x + k leaves the same remainder as x cube + 3x square - 3 when divided by x - 4.
Let R(x) be the remainder when 2x³ - 5x + k is divided by x - 4. By the remainder theorem, we know that R(4) = 109.
4 | 2 0 0 -5
8 32 128
--------
2 8 32 123
Therefore, when 2x³ - 5x + 123 is divided by x - 4, the remainder is 123.
Step 3:
We need to find the value of k.
Since the remainder is the same in both cases, we have:
R(x) = 2x³ - 5x + k - (x cube + 3x square - 3) = 2x³ - x² - 5x + (k + 3)
We know that R(4) = 109, so we have:
2(4)³ - 4² - 5(4) + (k + 3) = 109
Simplifying this equation, we get:
k = -150
Therefore, the value of k is -150.