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What is the value of c2-d2 if, c+d=7 and c-d=-2? (2 is supposed to be square in c2-d2, keyboard issues)?
2 Answers
- Ms. WorthLv 74 years ago
The expression c² - d² is a "Difference of Two Squares."
This kind of binomial is factored by memorization of the rule.
http://www.purplemath.com/modules/specfact.htm
c² - d² is factored as
(c + d)(c - d)
In this problem, you are given
c + d = 7
c - d = 2
Since
c² - d²..... = .......... (c + d) × (c - d), then
c² - d² must equal .... 7.... × ... 2
Answer:
c² - d² = 14
- ?Lv 74 years ago
(c + d)(c - d) = c² - d²
Therefor
c² - d² = (c + d)(c - d)
c² - d² = 7 * 2
c² - d² = 14 <––––––
