Digits, Grade 8, Volume 1, Homework Helper

1-6: TEKS Practice

• 1. If x = 36 and y = 25, is square root of x plus y end root rational or irrational? Simplify your answer.

• 2. After an accident, police can use the formula v equals 2 , square root of 5 l end root to estimate the speed, v, in miles per hour, that a car was traveling by measuring the length of the skid marks, L, in feet.

• a. Estimate the speed of a car that left skid marks 65 ft long. Round to the nearest tenth as needed.

• b. If the posted speed limit is 40 mi/h, was the car speeding?

• 3. Write 0.87 as a fraction in simplest form.

• 4. Write 0. , 72 bar as a fraction in simplest form.

• 5. Is square root of x squared , plus , y squared end root rational or irrational when x = 14 and y = 8? If you pick a whole number value for x, can you always find a whole number value for y to make the expression a rational number? Explain.

• 6. A couple wants to enclose a square garden with area 141 ft2. The wife says that they need about 47.6 ft of fence. The husband disagrees. He says they need about 11.9 ft of fence.

• a. Who is correct?

• b. What error did the person who found the incorrect length make?

• A. The person divided the area of the garden by 4 to find the side length.

• B. The person added 4 to the side length instead of multiplying by 4 to find the perimeter.

• C. The person squared the area instead of finding the square root to find the side length.

• D. The person found the side length of the garden, not the perimeter.

• c. Explain how you found the correct length of fence that the couple needs.

• 7. Think About the Process The length of a rectangle is twice the width. The area of the rectangle is 90 square units. Notice that you can divide the rectangle into two squares with equal area.

• a. How can you estimate the side length of each square?

• A. Estimate square root of 90 over 4 end root , . .

• B. Estimate square root of 90 . .

• C. Estimate square root of 45 . .

• D. Estimate square root of 45 over 4 end root , . .

• b. Estimate the length and width of the rectangle.

• 8. Error Analysis Your teacher asks you to write 5.75 × 10−4 in standard form. Your classmate gives an incorrect answer of 0.0000575.

• a. Write 5.75 × 10−4 in standard form.

• b. What was your classmate's likely error?

• A. Your classmate moved the decimal point 1 extra place to the left.

• B. Your classmate moved the decimal point 2 extra places to the left.

• C. Your classmate moved the decimal point 1 extra place to the right.

• D. Your classmate moved the decimal point 2 extra places to the right.

End ofPage 38