SOLUTION: Evaluating expression. My textbook has two problems; b^2 (squared) and (b)^2 where b is -2, to show apply exponent first and then apply the - sign so you get -4 in the first case.

Algebra ->  Expressions -> SOLUTION: Evaluating expression. My textbook has two problems; b^2 (squared) and (b)^2 where b is -2, to show apply exponent first and then apply the - sign so you get -4 in the first case.       Log On


   

Question 1110295: Evaluating expression. My textbook has two problems; b^2 (squared) and (b)^2 where b is -2, to show apply exponent first and then apply the - sign so you get -4 in the first case. The second case is the (-2)^2, so you get +4 since the - sign is enclosed so you apply the - sign value to the squaring. Later on the page it has 3b^2 (squared). So I read this as 3 times b^2, so it would be 3 times -2^2. Which would be; square the 2, apply the - sign and multiply by 3. 3(-4)= -12
Other people say the answer is -2^2 to get +4 and then multiply by 3.So 3(+4)=+12 If the first example shows to apply the exponent before negation, then shouldn't the question be written "evaluate 3(b)^2? to get +12?
Answer by greenestamps(13206) About Me  (Show Source):
You can put this solution on YOUR website!


"b^2" is NOT equal to -4 when b is -2.

When evaluating "b^2" for b=-2, you don't just erase the "b" and replace it with "-2" to get "-2^2".

"b^2" means you take whatever value b is and square it; (-2) squared is +4.

If you want to think in terms of evaluating an expression by replacing the symbol for the variable with the value of the variable, then put the value in parentheses -- that is, to evaluate "b^2" for b=-2, erase the b and replace it with (-2); then the expression is "(-2)^2".