A number is 1/7 of another number.the difference of the number is 18. find the numbers

The length of a rectangle is 4 meters less than twice its width. The are of a rectangle is 70m^2. Find the dimensions of the rec

igomit [66]

Answer:

The length is 7 m

The width is 10 m

Step-by-step explanation:

length = x

width = 2x - 4

length * width = area

It is given that the area is 70 $m^{2}$

From there

x * (2x - 4) = 70

$2x^{2}$ - 4x = 70

$2x^{2}$ - 4x - 70 = 0

$x^{2}$ - 2x - 35 = 0

Now we have a quadratic equation, which is a $x^{2}$ + bx + c = 0, where a $\neq$ 0

In this equation a = 1, b = -2 and c = -35

Discriminant (D) formula is b² - 4ac

D = $-2^{2}$ - 4 * 1 * (-35) = 144 > 0

This discriminant is more than 0, so there are two possible x

Their formulas are $\frac{- b - \sqrt{D} }{2a}$ and $\frac{- b + \sqrt{D} }{2a}$

$x_{1}$ = $\frac{- (-2) - \sqrt{144} }{2}$ = -5 < 0 (the length of the rectangle has to be more than 0, so we don't use this x)

$x_{2}$ = $\frac{- (-2) + \sqrt{144} }{2}$ = 7 > 0 (this one is right)

Calculating the dimensions

length = x = 7 (m)

width = 2x - 4 = 2 * 7 - 4 = 10 (m)

8 0

2 years ago

Find the equation of the line that goes through (-8,11) and is perpendicular to x= - 15. Write the equation in the form x = a, y

galben [10]

Answer:

y=11

Step-by-step explanation:

Hi there!

We want to find the equation of the line that passes through the point (-8, 11) and is perpendicular to x=-15

If a line is perpendicular to another line, it means that the slopes of those lines are negative and reciprocal; in other words, the product of the slopes is equal to -1

The line x=-15 has an undefined slope, which we can represent as 1/0, which is also undefined.

To find the slope of the line perpendicular to x=-15, we can use this equation (m is the slope):

$m_1*m_2=-1$

$m_1$ in this instance would be 1/0, so we can substitute it into the equation:

$\frac{1}{0} *m_2=-1$

Multiply both sides by 0

$m_2=0$

So the slope of the new line is 0

We can substitute it into the equation y=mx+b, where m is the slope and b is the y intercept:

y=0x+b

Now we need to find b:

Since the equation passes through the point (-8,11), we can use its values to solve for b.

Substitute -8 as x and 11 as y:

11=0(-8)+b

Multiply

11=0+b, or 11=b

So substitute into the equation:

y=0x+11

We can also write the equation as y=11

Hope this helps!

5 0

2 years ago

Help 10 pointssss!!!

kvasek [131]

Answer: Go to demos graphing

Step-by-step explanation:

7 0

2 years ago

Read 2 more answers

20 POINTS<br><br>please help and have a good weekend

Over [174]

A = 6 cm; B = 3 cm; C = 8 cm; D = 10 cm

The Surface area of the prism = 120 cm².

<h3>How to Find the Surface Area of Triangular Prism?</h3>

Surface area = Area of A + B + C + D

The side lengths are:

A = 6 cm

B = 3 cm

C = 8 cm

D = 10 cm

Surface area of the prism = 2(area of triangular face) + area of rectangle 1 + area of rectangle 2 + area of rectangle 3

Area of triangular face = 1/2(b)(h) = 1/2(8)(6) = 24 cm

Area of rectangle 1 = (length)(width) = (10)(3) = 30 cm²

Area of rectangle 2 = (length)(width) = (6)(3) = 18 cm²

Area of rectangle 3 = (length)(width) = (8)(3) = 24 cm²

Surface area of the prism = 2(24) + 30 + 18 + 24 = 120 cm².

Learn more about Surface Area of Triangular Prism on:

brainly.com/question/16147227

#SPJ1

4 0

1 year ago

A building is 70 feet tall. A blueprint of the building represents that length as 7 inches. What is the scale of the blueprint

matrenka [14]

Answer:

The scale of the blueprint is 10x smaller

Step-by-step explanation:

Divide. 70 divided by 7 is 10

8 0

3 years ago