Solve the Basic Equation: Finding Expressions Equal to 9

Exponent Rules with Negative Numbers

9= 9=

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Step-by-step video solution

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00:00 Break down to power
00:05 Let's break down the power to multiplication, excluding the sign
00:08 It seems this option is not suitable
00:12 Let's break down the power to multiplication, including the sign
00:16 This option is suitable
00:21 Let's break down the power to multiplication, excluding the sign
00:24 It seems this option is not suitable
00:27 And this is the solution to the question

Step-by-step written solution

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1

Understand the problem

9= 9=

2

Step-by-step solution

To solve this problem, we need to evaluate expressions by applying the rules of exponents and the effects of parentheses on negative numbers:

  • (3)2(-3)^2: When a negative number is squared, the result is positive. So, (3)2(-3)^2 means 3×3=9-3 \times -3 = 9.
  • (3)2-(-3)^2: This means 1×(3×3)-1 \times (-3 \times -3) because squaring a number negates the negative sign inside parentheses, resulting in 9-9.
  • (3)2-(3)^2: This equals 1×(3×3)=9-1 \times (3 \times 3) = -9, as the negative sign is outside the squared value.
  • 3-3: This is simply 3-3.

Only (3)2(-3)^2 equals 9, confirming it as the correct expression required by the problem.

Therefore, the solution to the problem is (3)2 (-3)^2 .

3

Final Answer

(3)2 (-3)^2

Key Points to Remember

Essential concepts to master this topic
  • Parentheses Rule: Negative numbers in parentheses change sign when squared
  • Technique: (3)2=(3)×(3)=9 (-3)^2 = (-3) \times (-3) = 9
  • Check: Only (3)2 (-3)^2 gives positive 9, others give -9 or -3 ✓

Common Mistakes

Avoid these frequent errors
  • Confusing placement of negative signs and parentheses
    Don't treat (3)2 -(3)^2 and (3)2 (-3)^2 as the same = one gives -9, the other gives 9! The parentheses placement completely changes the result. Always square the negative number first when it's inside parentheses.

Practice Quiz

Test your knowledge with interactive questions

\( (-2)^7= \)

FAQ

Everything you need to know about this question

Why does squaring a negative number make it positive?

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When you multiply two negative numbers, you get a positive result! So (3)2=(3)×(3)=+9 (-3)^2 = (-3) \times (-3) = +9 . Think of it as negative times negative equals positive.

What's the difference between (3)2 (-3)^2 and (3)2 -(3)^2 ?

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The parentheses make all the difference! (3)2 (-3)^2 means square the negative three = 9. But (3)2 -(3)^2 means take the negative of three squared = -9.

How do I remember which expressions equal 9?

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Look for the negative number inside parentheses being squared. Only (3)2 (-3)^2 has the negative completely enclosed before squaring, giving you a positive result.

Why is (3)2 -(-3)^2 equal to -9?

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Work from inside out: first (3)2=9 (-3)^2 = 9 , then apply the outer negative sign: (9)=9 -(9) = -9 . The double negative doesn't cancel here because of order of operations!

Can a negative number ever equal 9?

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No! The number 9 is positive, so no negative number or negative expression can equal 9. That's why 3 -3 is immediately ruled out as an answer.

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