Solve: a²÷a + a³×a⁵ Expression Using Laws of Exponents

Exponent Laws with Addition of Terms

Solve the exercise:

a2:a+a3a5= a^2:a+a^3\cdot a^5=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Simplify the following expression
00:05 Rewrite the division operation as a fraction
00:13 According to the laws of exponents when dividing with the same base(A)
00:18 With different exponents(M,N) where M is in the numerator
00:21 We obtain the same base(A) with exponent(M-N)
00:24 Let's apply this to the question
00:27 We keep the base(A) and subtract the exponents(2-1)
00:38 According to the laws of exponents, multiplication with the same base(A) with exponents N,M
00:42 Will be equal to the same base(A) with exponent (N+M)
00:46 Let's apply it to the question
00:49 We keep the base(A) and add the exponents(3+5)
00:52 Calculate all the exponents
01:00 Factor out the common base A
01:06 This is the simplified expression and the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve the exercise:

a2:a+a3a5= a^2:a+a^3\cdot a^5=

2

Step-by-step solution

First we rewrite the first expression on the left of the problem as a fraction:

a2a+a3a5 \frac{a^2}{a}+a^3\cdot a^5 Then we use two properties of exponentiation, to multiply and divide terms with identical bases:

1.

bmbn=bm+n b^m\cdot b^n=b^{m+n}

2.

bmbn=bmn \frac{b^m}{b^n}=b^{m-n}

Returning to the problem and applying the two properties of exponentiation mentioned earlier:

a2a+a3a5=a21+a3+5=a1+a8=a+a8 \frac{a^2}{a}+a^3\cdot a^5=a^{2-1}+a^{3+5}=a^1+a^8=a+a^8

Later on, keep in mind that we need to factor the expression we obtained in the last step by extracting the common factor,

Therefore, we extract from outside the parentheses the greatest common divisor to the two terms which are:

a a We obtain the expression:

a+a8=a(1+a7) a+a^8=a(1+a^7) when we use the property of exponentiation mentioned earlier in A.

a8=a1+7=a1a7=aa7 a^8=a^{1+7}=a^1\cdot a^7=a\cdot a^7

Summarizing the solution to the problem and all the steps, we obtained the following:

a2a+a3a5=a(1+a7) \frac{a^2}{a}+a^3\cdot a^5=a(1+a^{7)}

Therefore, the correct answer is option b.

3

Final Answer

a(1+a7) a(1+a^7)

Key Points to Remember

Essential concepts to master this topic
  • Division Rule: When dividing powers with same base, subtract exponents
  • Multiplication Rule: a3a5=a3+5=a8 a^3 \cdot a^5 = a^{3+5} = a^8 when multiplying powers
  • Factoring Check: Extract common factor a from a+a8 a + a^8 to get a(1+a7) a(1 + a^7)

Common Mistakes

Avoid these frequent errors
  • Adding exponents when dividing powers
    Don't add exponents when dividing: a2÷aa3 a^2 ÷ a ≠ a^3 ! This gives a3+a8=a11 a^3 + a^8 = a^{11} which is wrong. Always subtract exponents when dividing: a2÷a=a21=a1 a^2 ÷ a = a^{2-1} = a^1 .

Practice Quiz

Test your knowledge with interactive questions

\( 112^0=\text{?} \)

FAQ

Everything you need to know about this question

Why can't I just add all the exponents together?

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You can only add exponents when multiplying powers with the same base. Here we have division (subtract exponents) plus multiplication (add exponents). They're separate operations!

How do I know when to factor out the common term?

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Look for the greatest common factor in all terms. Since we have a+a8 a + a^8 , the GCF is a a . Factor it out: a(1+a7) a(1 + a^7) .

What does the colon symbol (:) mean in math?

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The colon (:) means division, just like the ÷ symbol. So a2:a a^2:a is the same as a2÷a a^2 ÷ a or a2a \frac{a^2}{a} .

Can I simplify this expression differently?

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No, a(1+a7) a(1 + a^7) is the simplest factored form. You could expand it back to a+a8 a + a^8 , but factored form is usually preferred as the final answer.

Why isn't the answer just a^9?

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That would only be true if we were multiplying a2a7 a^2 \cdot a^7 . But we have a1+a8 a^1 + a^8 (addition), which cannot be simplified to a single power.

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