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1. Find the numbers a, b, c such that

2x4 + 2x3 +5x2 + 3x + 3 = (x2 + x +1)(ax2+bx+c)
for all values of x.​

User Stuhlo
by
3.4k points

1 Answer

4 votes

Answer:

a = 2

b = 0

c = 3

Explanation:

if I understand correctly the problem should look like

2x⁴ + 2x³ + 5x² + 3x + 3 = (x² + x + 1)(ax² + bx + c)

let's calculate the right side

ax⁴ + ax³ + ax² + bx³ + bx² + bx + cx² + cx + c

as there is only one term of x⁴, we know a = 2

as there is only one term without any x, we know c = 3

now we get

2x⁴ + 2x³ + 2x² + bx³ + bx² + bx + 3x² + 3x + 3

remember, that is equal to

2x⁴ + 2x³ + 5x² + 3x + 3

after subtracting 2x⁴ and 3 from both sides we get

2x³ + 5x² + 3x = 2x³ + 2x² + bx³ + bx² + bx + 3x² + 3x

we subtract 2x³ and 3x from both sides and get

5x² = 2x² + bx³ + bx² + bx + 3x² = 5x² + bx³ + bx² + bx

we subtract 5x² from both sides and get

0 = bx³ + bx² + bx

=> b must be 0 to make this true for all values of x

User Christal
by
3.9k points