A binary operation Δ is defined by aΔb = a + b + 1 for any numbers a and b. Find the inverse of the real number 7 under the operation Δ, if the identity element is -1
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Correct Answer: Option B
Explanation:
a*e = a + e + 1 = a
implies e+ 1 = 0
− e = -1
7 * e = -1
− a + 7 + 1 = -1
a + 8 = -1
a+8 = -1
a = -1-8
a = -9
a*e = a + e + 1 = a
implies e+ 1 = 0
− e = -1
7 * e = -1
− a + 7 + 1 = -1
a + 8 = -1
a+8 = -1
a = -1-8
a = -9