On dividing x3-3x^2+5x-3 by a polynomial p(x) the quotient and remainder are x-3 and 7x-9 find p(x)
Answers
ANSWER
CONCEPT
SOLUTION
We have to find value of divisor
given
dividend = x3-3x^2+5x-3
divisor = p(x)
quotient = (x-3)
remainder = 7x-9
Put value of given quantities
x3-3x^2+5x-3 = p(x) × (x-3) + 7x-9
p(x) = x3-3x^2+5x-3 -7x+9
x-3
p(x) = x3-3x^2-2x+6
x-3
since ( x-3) is a factor of x3-3x^2-2x+6
on dividing we get
p(x) = x^2 -2
Question:
On dividing x³-3x²+5x-3 by a polynomial p(x) the quotient and remainder are x-3 and 7x-9 find p(x).
Solution:
Here,
Divisor = p(x)
Let the dividend, quotient and remainder be g(x) , q(x) and r(x) respectively.
By Division Algorithm,
Dividend = Divisor x quotient + Remainder
g(x) = p(x) × q(x) + r(x)
We have,
g(x) [dividend] = x³ - 3x² +5x -3
q(x) [quotient] = x - 3
r(x) [remainder] = 7x-9
p(x) [divisor] = ?
Now,
Putting values
x³ - 3x² +5x -3 = p(x) ×( x - 3) + 7x - 9
x³ - 3x² +5x -3 - (7x-9) = p(x) x (x-3)
x³ - 3x² +5x -3 -7x +9 = p(x) × (x-3)
x³ - 3x² -2x + 6 = p(x) × (x -3)
x³ - 3x² -2x +6/(x-3) = p(x)
Now dividing x³ -3x² -2x +6 by x-3
Here,
x² - 2
x-3 | x³ -3x² -2x +6
x³ -3x²
- + (both are cancelled)
-2x + 6
-2 x + 6
+ - (again both cancelled)
0 <= remainder
Hence, p(x) = x² - 2
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