Grade 8

Help Questions

8th Grade Math › Grade 8

Questions 1 - 10

Convert the given value to scientific notation.

Explanation

Scientific notation is used to simplify exceptionally complex numbers and to quickly present the number of significant figures in a given value. The value is converted to an exponent form using base ten, such that only a single-digit term with any given number of decimal places is used to represent the significant figures of the given value. Non-significant zeroes can be omitted from the leading term, and represented only in the base ten exponent.

The given number has five significant figures (100.43), so there will be five digits multiplied by the base ten term.

To generate the single-digit leading term the decimal must be placed after the 1 (1.0043). Then count the digits to the right of the decimal to determine the change in decimal placement (the decimal moves past the two zeroes). Our ten will be raised to the power of two because there are two digits to the right of the final decimal placement.

Our final answer is

Evaluate: $\dpi{100} (3^{3})^{2}$

$\dpi{100} 3^{6}$

$\dpi{100} 3^{5}$

$\dpi{100} 243$

$\dpi{100} 729$

Explanation

A power raised to a power indicates that you multiply the two powers.

$\dpi{100} (3^{3})^{2}=3^{3\cdot 2}=3^{6}$

Evaluate: $\dpi{100} (3^{3})^{2}$

$\dpi{100} 3^{6}$

$\dpi{100} 3^{5}$

$\dpi{100} 243$

$\dpi{100} 729$

Explanation

A power raised to a power indicates that you multiply the two powers.

$\dpi{100} (3^{3})^{2}=3^{3\cdot 2}=3^{6}$

Which of the following answer choices displays an irrational number?

$\sqrt{17}$

$\frac{7}{9}$

Explanation

Our answer choices consist of two types of numbers: rational numbers and irrational numbers. In order to correctly answer this question, we need to know the difference between the two types of numbers.

Rational numbers are numbers that we use most often, and can be written as a simple fraction.

Irrational numbers cannot be written as fractions, and are numbers that have decimal places that never repeat or end.

In this case, $\sqrt{17}$ is our only irrational number because it cannot be written as a simple fraction.

What is the slope of the line that passes through the points and ?

Explanation

The slope of a line is sometimes referred to as "rise over run." This is because the formula for slope is the change in y-value (rise) divided by the change in x-value (run). Therefore, if you are given two points, $(x_{1},y_{1})$ and $(x_{2},y_{2})$ , the slope of their line can be found using the following formula: $slope=(y_{1}-y_{2})/(x_{1}-x_{2})$

This gives us .

Are the two shapes shown in the coordinate plane congruent? If so, what transformation did the red shape undergo from the orange shape?

Yes, translation to the left

Yes, $90^\circ$ rotation

Yes, refection over the y-axis

Explanation

In order to solve this problem, we first need to know what "congruent" means. For two shapes to be congruent, they need to be the same shape and the same size. The shape can go through a transformation—rotation, translation, or reflection—but nothing else about the original shape can be changed for two shapes to be congruent.

Also, let's recall the types of transformations:

Rotation: A rotation means turning an image, shape, line, etc. around a central point.

Translation: A translation means moving or sliding an image, shape, line, etc. over a plane.

Reflection: A reflection mean flipping an image, shape, line, etc. over a central line.

For this question, we can tell that the triangles are not the same size, the red triangle is smaller; thus, the triangles are not congruent.

What is the slope of the line that passes through the points and ?

Explanation

This gives us .

In order to get to work, Jeff leaves home and drives 4 miles due north, then 3 miles due east, followed by 6 miles due north and, finally, 7 miles due east. What is the straight line distance from Jeff’s work to his home?

2√5

10√2

6√2

Explanation

Jeff drives a total of 10 miles north and 10 miles east. Using the Pythagorean theorem (a2+b2=c2), the direct route from Jeff’s home to his work can be calculated. 102+102=c2. 200=c2. √200=c. √100√2=c. 10√2=c

Are the two shapes shown in the coordinate plane congruent? If so, what transformation did the red shape undergo from the orange shape?

Yes, translation down and to the left

Yes, $90^\circ$ rotation

Yes, refection over the x-axis

Explanation

Also, let's recall the types of transformations:

Rotation: A rotation means turning an image, shape, line, etc. around a central point.

Translation: A translation means moving or sliding an image, shape, line, etc. over a plane.

Reflection: A reflection mean flipping an image, shape, line, etc. over a central line.

For this question, we can tell that the triangles are not the same size, the red triangle is smaller; thus, the triangles are not congruent.

Calculate the length of the missing side of the provided triangle. Round the answer to the nearest whole number.

$37\textup{ cm}$

$34\textup{ cm}$

$35\textup{ cm}$

$36\textup{ cm}$

Explanation

The provided triangle is a right triangle. We know this because the angle marker in the left corner of the triangle indicates that the triangle possesses a right or $90^\circ$ angle. When a triangle includes a right angle, the triangle is said to be a "right triangle."

We can use the Pythagorean Theorem to help us solve this problem.

The Pythagorean Theorem states that for right triangles, the square of the hypotenuse is equal to the sum of the square of the other two sides. In other terms: