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C) what is an expression for C in terms of?

please help​

C) what is an expression for C in terms of? please help​-example-1
User Ognjen
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1 Answer

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Answer:

This one is tricky! Let x be any integer. We can make any other integer we want by taking Ax + B, where A and B are integers too. The square of this integer is than (Ax+B)2. When expanded, this comes out to

A2x2 + 2ABx + B2. We've now made an expression which is the square of an integer for all integers x!

Now, we can set the coefficients of powers of x in the problem and in A2x2 + 2ABx + B2 equal to eachother.

A2 = a2

2AB = c

B2 = b2

Since a is positive, a = A, if A is positive. If A is negative, a = -A (or A = -a). The same logic leads to

b = B, if B is positive. If B is negative, b = -B (or B = -b).

Since c is positive, we know that A and B are either both positive or both negative. This leads to 2 cases:

Case 1: A is positive, B is positive. Then A = a, B = b, and

c = 2ab.

Case 2: A is negative, B is negative. Then A = -a, B = -b, and

c = 2(-a)(-b) = 2ab.

Since both cases lead to the same answer, we conclude that

c = 2ab.

User Aldana
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