Solve: 4×sqrt(0.49) + 4² | Mixed Operations Expression

Order of Operations with Square Roots

4×0.49+42= 4\times\sqrt{0.49}+4^2=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:07 Let's solve this expression together.
00:11 First, we'll break down zero point four nine into zero point seven squared.
00:17 Remember, the square root of a squared number cancels out the square.
00:22 Always solve multiplication and division before tackling addition and subtraction.
00:29 Use vertical multiplication to find the product easily.
00:37 And remember, any number multiplied by zero is always zero.
00:50 Be aware of where you place the decimal point.
00:55 Now, continue solving the expression step by step.
00:59 Great job! That's how you find the solution.

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

4×0.49+42= 4\times\sqrt{0.49}+4^2=

2

Step-by-step solution

To solve the expression 4×0.49+42= 4\times\sqrt{0.49}+4^2 = , we will follow the order of operations, which prioritizes operations inside parentheses, exponents and roots, followed by multiplication and division, and finally addition and subtraction.

1. Calculate the Square Root:
The first step is to solve the square root part of the expression. 0.49 \sqrt{0.49} .
0.49 0.49 is a simple decimal number whose square root is 0.7 0.7 , because 0.7×0.7=0.49 0.7 \times 0.7 = 0.49 .
So,0.49=0.7 \sqrt{0.49} = 0.7 .

2. Multiply:
Next, we multiply the result of the square root by 4:
4×0.7=2.8 4 \times 0.7 = 2.8 .

3. Calculate the Power:
Evaluate 42 4^2 .
42=16 4^2 = 16 , because 4×4=16 4 \times 4 = 16 .

4. Addition:
Now, add the results from the previous steps:
2.8+16=18.8 2.8 + 16 = 18.8 .

The final result of the expression 4×0.49+42 4\times\sqrt{0.49}+4^2 is 18.8 \boxed{18.8} .

3

Final Answer

18.8

Key Points to Remember

Essential concepts to master this topic
  • Order Rule: Follow PEMDAS - roots first, then multiplication, then addition
  • Technique: Calculate 0.49=0.7 \sqrt{0.49} = 0.7 , then 4×0.7=2.8 4 \times 0.7 = 2.8
  • Check: Verify each step: 0.7 × 0.7 = 0.49, then 2.8 + 16 = 18.8 ✓

Common Mistakes

Avoid these frequent errors
  • Adding before completing all operations
    Don't add 0.49 + 16 = 16.49 first! This ignores the square root and multiplication. The order of operations requires you to complete roots and multiplication before addition. Always follow PEMDAS: calculate 0.49 \sqrt{0.49} first, then multiply by 4, then add 42 4^2 .

Practice Quiz

Test your knowledge with interactive questions

\( \sqrt{4}= \)

FAQ

Everything you need to know about this question

Why do I calculate the square root before multiplying by 4?

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Because of the order of operations (PEMDAS)! Roots and exponents come before multiplication and division. So you must find 0.49=0.7 \sqrt{0.49} = 0.7 first, then multiply: 4×0.7=2.8 4 \times 0.7 = 2.8 .

How do I find the square root of 0.49?

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Think: what number times itself equals 0.49? Since 0.7×0.7=0.49 0.7 \times 0.7 = 0.49 , we know 0.49=0.7 \sqrt{0.49} = 0.7 . You can also recognize that 0.49 = 49/100, so 0.49=49/100=7/10=0.7 \sqrt{0.49} = \sqrt{49}/\sqrt{100} = 7/10 = 0.7 .

What if I calculated 4² as 8 instead of 16?

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Double-check exponents! 42 4^2 means 4 × 4 = 16, not 4 × 2 = 8. The small 2 tells you to multiply 4 by itself, not by 2.

Can I use a calculator for the square root?

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Yes! But try to recognize common square roots like 0.25=0.5 \sqrt{0.25} = 0.5 , 0.49=0.7 \sqrt{0.49} = 0.7 , and 0.81=0.9 \sqrt{0.81} = 0.9 . This builds your number sense!

Why is the final answer 18.8 and not 19?

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Because we're working with exact values! 4×0.7=2.8 4 \times 0.7 = 2.8 exactly, and 2.8+16=18.8 2.8 + 16 = 18.8 exactly. Never round until the very end unless the problem asks you to.

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