Solve the Equation: a^4 + 7a - 5 = 2a + a^4 + 3a - (-a)

Linear Equations with Variable Elimination

a4+7a5=2a+a4+3a(a) a^4+7a-5=2a+a^4+3a-(-a)

a=? a=?

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve
00:10 Negative times negative is always positive
00:22 Group like terms
00:29 Simplify what we can
00:34 We want to isolate the unknown A
00:40 Let's arrange the equation so that one side has only A
00:51 Convert from negative to positive
00:57 Negative divided by negative is always positive
01:03 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

a4+7a5=2a+a4+3a(a) a^4+7a-5=2a+a^4+3a-(-a)

a=? a=?

2

Step-by-step solution

First, let's isolate a from the parentheses in the equation on the right side. We'll remember that minus times minus becomes plus, so we get the equation:

a4+7a5=2a+a4+3a+a a^4+7a-5=2a+a^4+3a+a

Let's continue solving the equation on the right side by adding 2a+3a+a=5a+a=6a 2a+3a+a=5a+a=6a

Now the equation we got is:

a4+7a5=6a+a4 a^4+7a-5=6a+a^4

Let's divide both sides by a4 a^4 and we get:

7a5=6a 7a-5=6a

Now let's move 6a to the left side and the number 5 to the right side, remembering to change the plus and minus signs accordingly.

The equation we got now is:

7a6a=5 7a-6a=5

Let's solve the subtraction and we get:

1a=5 1a=5

Let's divide both sides by 1 and we find that a=5 a=5

3

Final Answer

5 5

Key Points to Remember

Essential concepts to master this topic
  • Simplify: Handle negative signs carefully: -(-a) becomes +a
  • Technique: Subtract a4 a^4 from both sides: 7a5=6a 7a - 5 = 6a
  • Check: Substitute a = 5 back: 7(5)5=6(5) 7(5) - 5 = 6(5) gives 30 = 30 ✓

Common Mistakes

Avoid these frequent errors
  • Incorrectly handling the double negative -(-a)
    Don't leave -(-a) as -a = wrong simplification! This creates 5a instead of 6a on the right side, leading to a = -5. Always remember that minus times minus equals plus, so -(-a) = +a.

Practice Quiz

Test your knowledge with interactive questions

Solve for \( b \):

\( 8-b=6 \)

FAQ

Everything you need to know about this question

Why do the a4 a^4 terms cancel out?

+

When you have the same term on both sides of an equation, you can subtract it from both sides. Since a4 a^4 appears on both sides, subtracting it leaves you with a simpler linear equation.

What does -(-a) actually mean?

+

The double negative -(-a) means "the opposite of negative a" which equals positive a. Think of it as: minus times minus equals plus, so -(-a) = +a.

How do I combine like terms on the right side?

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Add all the 'a' terms together: 2a+3a+a=6a 2a + 3a + a = 6a . Remember that 'a' by itself means 1a 1a , so you're adding 2 + 3 + 1 = 6.

Can I divide by a4 a^4 like the explanation shows?

+

Actually, that's incorrect! You should subtract a4 a^4 from both sides instead. Dividing assumes a0 a ≠ 0 and can lead to losing solutions.

How can I check if a = 5 is really correct?

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Substitute a = 5 into the original equation:

  • Left side: 54+7(5)5=625+355=655 5^4 + 7(5) - 5 = 625 + 35 - 5 = 655
  • Right side: 2(5)+54+3(5)+5=10+625+15+5=655 2(5) + 5^4 + 3(5) + 5 = 10 + 625 + 15 + 5 = 655

Since both sides equal 655, a = 5 is correct!

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