Question

Divide x4 + 7 by x - 3.. A] x³ - 3x² - 9x - 27 R 88. B] x³ + 3x² + 9x - 27 R -74. C] x³ + 3x² + 9x + 27 R 88

Answer 1

 divide a polynomial p(x) by (x-3). Add and subtract the multiple of (x-3) that has the same highest-power term as p(x), then simplify to get a smaller-degree polynomial r(x) plus multiple of (x-3). 

The multiple of (x-3) that has x^4 as its leading term is x^3(x-3) = x^4 - 3x^3. So write: 

x^4 + 7 = x^4 + 7 + x^3(x - 3) - x^3(x - 3) 
= x^4 + 7 + x^3(x - 3) - x^4 + 3x^3 
= x^3(x - 3) + 3x^3 + 7 

That makes r(x) = 3x^3 + 7. Do the same thing to reduce r(x) by adding/subtracting 3x^2(x - 3) = 3x^3 - 9x^2: 

= x^3(x - 3) + 3x^3 + 7 + 3x^2(x - 3) - (3x^3 - 9x^2) 
= x^3(x - 3) + 3x^2(x - 3) + 9x^2 + 7 

Again to reduce 9x^2 + 7: 
= x^3(x - 3) + 3x^2(x - 3) + 9x^2 + 7 + 9x(x - 3) - (9x^2 - 27x) 
= x^3(x - 3) + 3x^2(x - 3) + 9x(x - 3) + 27x + 7 

And finally write 27x + 7 as 27(x - 3) + 88; 
x^4 + 7 = x^3(x - 3) + 3x^2(x - 3) + 9x(x - 3) + 27(x - 3) + 88 

Factor out (x - 3) in all but the +88 term: 
x^4 + 7 = (x - 3)(x^3 + 3x^2 + 9x + 27) + 88 

That means that: 
(x^4 + 7) / (x - 3) = x^3 + 3x^2 + 9x + 27 with a remainder of 88

Answer 2

Answer:

x^3   +  3x^2    +   9x    +  27   + r 88

Step-by-step explanation: