Question

If a binary operation is defined by \(a\ \mathrm{o}\ b=3a+b\), then \((2\ \mathrm{o}\ 3)\ \mathrm{o}\ 5=\) ?

• A. \(28\)
• B. \(32\)
• C. \(36\)
• D. \(22\)

Hint:

When a custom operation is given by a formula, evaluate exactly in the stated order: compute the inner operation first, then apply the rule again.

Answer 1

The Correct Option is B

Operate step by step (left to right):
1) First compute \(2\ \mathrm{o}\ 3\): \[ 2\ \mathrm{o}\ 3=3(2)+3=6+3=9. \] 2) Now use this result with \(5\): \[ (2\ \mathrm{o}\ 3)\ \mathrm{o}\ 5=9\ \mathrm{o}\ 5=3(9)+5=27+5=32. \] Hence the value is \(32\).