Multiply: (x - 1)(x + 1)(x - 3)(x + 3)?

Question

Multiply: (x - 1)(x + 1)(x - 3)(x + 3)

a) x4 - 10x2 + 9
b) x2 - 10x + 9
c) x4 - x2 + 3
d) 2x4 - 10x2 + 19

Answer 1

Do it in two steps.

(x - 1)(x + 1) = x^2 - 1

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

(x^2 - 1) (x^2 - 9) = x^4 - 10x^2 + 9

So a is the answer.

Answer 2

(x-1)(x+1)(x-3)(x+3
=(x^2-1))(x^2-9)
=x^4-10x^2+9 ANS. OPtion d).

Answer 3

(x - 1)(x + 1)(x - 3)(x + 3)
(x - 1)(x + 1) * (x - 3)(x + 3)
(x^2 + 1x - 1x - 1) * (x^2 + 3x - 3x -9)
(x^2 - 1) * (x^2 - 9)
(x^2 - 1)(x^2 - 9)
(x^4 - 9x^2 - 1x^2 + 9)
(x^4 - 10x^2 + 9)

Thus the answer is (A) based on assuming in your answer you left out the '^' (to denote raising to a power)

Answer 4

formula (a-b)(a+b) =a^2-b^2

so (x-1) (x+1) = (x^2-1) and (x-3)(x+3) = (x^2-9)

(x^2-1) (x^2-9) = x^4-10x^2+9

answer a) correct

Answer 5

From observation: you would have terms x4 and +9

Since you will obtain by-terms of -1x^2-9x^2 = -10x^2

Hence: the answer is (a)

Answer 6

a is correct. multiply the first two brackets to get (x^2-1) then multiply the 2nd two brackets to get (x^2-9), then multiply these two brackets together. Man this is going back a long time for me, grade 9 math!

Answer 7

(x - 1)(x + 1)(x - 3)(x + 3)
= (x^2-1) (x^2-9)
= x^4-10x^2+9
ANS = a)

Answer 8

(x-1)(x+1) is in the form
(a+b)(a-b)=a^2-b^2)
similarly
for
(x-3)(x+3)=x^2-9
(x-1)(x+1)=x^2-1
multiplying we get



x^4-x^2-9x^2+9
=x^4-10x^2+9
a

Answer 9

See: If f(x)=3x^(7)-4x^(-3)+1x-3 Then f'(x)=21x^(6)+12x^(-4)+1

Answer 10

(x-1)(x+1)(x-3)(x+3)
=(x2+x-x-1)(x2-3x+3x-9)
=(x2-1)(x2-9)
=x4-9x2-x2+9
=x4-10x2+9