expand and simplify (7x - 3y)(7x + 3y)?

2008-02-26 9:22 am

回答 (6)

2008-02-26 9:36 am

✔ 最佳答案

49x² + 21xy - 21xy - 9y²
49x² - 9y²

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2008-02-26 5:35 pm

(7x - 3y)(7x + 3y)
= 49x^2 - 21xy + 21xy - 9y^2
= 49x^2 - 9y^2

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2008-02-26 5:27 pm

49x^2-9y^2

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2008-02-26 5:42 pm

hi!

expand: 49x^2 + 21xy - 21xy - 9y^2

simplify: 49x^2 - 9y^2

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2008-02-26 5:27 pm

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

a = 7x
b = 3y

and you'll get

(49x^2 - 9y^2)

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2008-02-26 6:01 pm

(7x - 3y)(7x + 3y)
= 49x^2 - 21xy + 21xy - 9y^2
= 49x^2 - 9y^2

👍 0 👎 2