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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

2007-08-14 03:16:51 · 10 answers · asked by song_fiend 2 in Science & Mathematics Mathematics

10 answers

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.

2007-08-14 03:35:08 · answer #1 · answered by Swamy 7 · 0 0

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

2007-08-14 03:54:33 · answer #2 · answered by Anonymous · 0 0

(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)

2007-08-14 04:22:45 · answer #3 · answered by Ironman 2 · 0 0

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

2007-08-14 03:23:31 · answer #4 · answered by maussy 7 · 1 0

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)

2007-08-14 03:51:22 · answer #5 · answered by ah_then123 1 · 0 0

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!

2007-08-14 03:30:05 · answer #6 · answered by Kevin D (RIP Adam Yauch MCA) 7 · 0 0

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

2007-08-14 03:39:43 · answer #7 · answered by harry m 6 · 0 0

(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

2007-08-14 03:24:49 · answer #8 · answered by srinu710 4 · 0 0

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

2016-05-17 09:57:08 · answer #9 · answered by geneva 3 · 0 0

(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

2007-08-14 03:40:52 · answer #10 · answered by @@.carlo 2 · 0 0

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