Solve (9+17x)×(6+1)=420: Find the Value of X

Linear Equations with Order of Operations

(9+17x)×(6+1)=420 (9+17x)\times(6+1)=420

Calculate a X

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find X
00:03 Make sure to open parentheses properly
00:07 Each term in parentheses multiplies each term in the second parentheses
00:25 Solve each multiplication and then sum
00:50 Collect like terms
01:00 Isolate X
01:31 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

(9+17x)×(6+1)=420 (9+17x)\times(6+1)=420

Calculate a X

2

Step-by-step solution

We begin by solving the addition exercise in the right parenthesis:

(9+17x)×7=420 (9+17x)\times7=420

We then multiply each of the terms inside the parentheses by 7:

(9×7)+(17x×7)=420 (9\times7)+(17x\times7)=420

We continue by solving each of the exercises inside of the parentheses:

63+119x=420 63+119x=420

Following this we rearrange the sections whilst maintaining the appropriate sign:

119x=42063 119x=420-63

119x=357 119x=357

Finally we divide the two parts by 119:

119119x=357119 \frac{119}{119}x=\frac{357}{119}

x=3 x=3

3

Final Answer

3

Key Points to Remember

Essential concepts to master this topic
  • Order of Operations: Simplify parentheses first, then multiply or divide
  • Distribution: Multiply 7 by each term: 7×9=63 7 \times 9 = 63 and 7×17x=119x 7 \times 17x = 119x
  • Verification: Check by substituting x = 3: (9+51)×7=60×7=420 (9+51) \times 7 = 60 \times 7 = 420

Common Mistakes

Avoid these frequent errors
  • Ignoring order of operations
    Don't solve the multiplication first and ignore the addition in parentheses = wrong setup! This breaks the fundamental rule that parentheses come before multiplication. Always simplify what's inside parentheses first, then multiply.

Practice Quiz

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FAQ

Everything you need to know about this question

Why do I need to solve (6+1) first?

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The order of operations (PEMDAS) says parentheses come first! You must calculate 6+1=7 6+1=7 before multiplying by the other expression.

Can I distribute the multiplication before simplifying the parentheses?

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Technically yes, but it's much harder! You'd have to distribute (9+17x) (9+17x) to both 6 and 1 separately. It's easier to simplify (6+1)=7 (6+1)=7 first.

How do I know when to move terms to the other side?

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Move terms to isolate the variable! When you have 63+119x=420 63+119x=420 , subtract 63 from both sides to get 119x=357 119x=357 .

What if I get a decimal answer instead of 3?

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Check your arithmetic! Common errors include forgetting to simplify (6+1) (6+1) or making calculation mistakes with 42063=357 420-63=357 or 357÷119=3 357÷119=3 .

How can I check if x = 3 is correct?

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Substitute back into the original equation: (9+17×3)×(6+1)=(9+51)×7=60×7=420 (9+17 \times 3) \times (6+1) = (9+51) \times 7 = 60 \times 7 = 420

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