All categories

3 years ago

What is (3x-4) (7x+4)

Mathematics

2 answers:

d1i1m1o1n [39]3 years ago

7 0

Answer:21x^2-16x-16

Step-by-step explanation:

(3x)(7x)+(3x)(4)+(−4)(7x)+(−4)(4) =

21x^2+12x−28x−16

21x^2−16x−16

enot [183]3 years ago

6 0

Answer:

21x^2 -16x -16

Step-by-step explanation:

This is a basic multiplication question,

We all know that (a+b)(c+d)=ac+ad+bc+bd

Here,

a = 3x

b = -4

c = 7x

d = 4

Therefore,

3x*7x + 3x*4 + (-4)*7x + (-4)*4

=> 21x^2 +12x - 28x -16

=> 21x^2 -16x -16

You might be interested in

3/4x+3y=12 for x when y=5

Karolina [17]

Solve for x by simplifying both sides of the equation, then isolating the variable.
x = -4
Hope this helps! :)
Happy New Years!

4 0

3 years ago

Emily is a diver. Today she descended to a

kotegsom [21]

She was at 40 feet below, she swam up getting so she was then at 40-10 = 30 feet below sea level.

She the swan 4 feet down so she ended up at 30 + 4 = 34 feet below sea level.

The answer is 34 feet below sea level (-34)

4 0

2 years ago

Read 2 more answers

The perimeter of a triangular field is 120m. Two of the sides are 21m and 40m.Calculate the largest angle of the field.

Mama L [17]

Answer:

the largest angle of the field is 149⁰

Step-by-step explanation:

Given;

perimeter of the triangular filed, P = 120 m

length of two known sides, a and b = 21 m and 40 m respectively

The length of the third side is calculated as follows;

a + b + c = P

21 m + 40 m + c = 120 m

61 m + c = 120 m

c = 120 m - 61 m

c = 59 m

↓ ↓

A → → → → → → → → → → → C

Consider ABC as the triangular field;

Angle A is calculated by applying cosine rule;

$a^2 = b^2 + c^2 - 2bc \ Cos A\\\\Cos \ A = \frac{b^2 + c^2 - a^2}{2bc} \\\\Cos \ A = \frac{40^2 + 59^2 - 21^2}{2 \times 40 \times 59} \\\\Cos \ A = 0.983\\\\A = Cos ^{-1} (0.983)\\\\A = 10.6 \ ^0$

Angle B is calculated as follows;

$Cos \ B = \frac{a^2 + c^2 - b^2}{2ac} \\\\Cos \ B = \frac{21^2 + 59^2 - 40^2}{2 \times 21 \times 59} \\\\Cos \ B = 0.937\\\\B= Cos ^{-1} (0.937)\\\\B = 20.5 \ ^0$

Angle C is calculated as follows;

$Cos \ C = \frac{a^2 + b^2 - c^2}{2ab} \\\\Cos \ C = \frac{21^2 + 40^2 - 59^2}{2 \times 21 \times 40} \\\\Cos \ C = -0.857\\\\C = Cos ^{-1} (-0.857)\\\\C = 149\ ^0$

Therefore, the largest angle of the field is 149⁰.

8 0

3 years ago

jenna's rectangular garden borders a wall. she buys 80 ft of fencing. what are the dimensions of the garden that will maximize i

FrozenT [24]

Answer:

The dimensions are x =20 and y=20 of the garden that will maximize its area is 400

Step-by-step explanation:

Step 1:-

let 'x' be the length and the 'y' be the width of the rectangle

given Jenna's buys 80ft of fencing of rectangle so the perimeter of the rectangle is 2(x +y) = 80

x + y =40

y = 40 -x

now the area of the rectangle A = length X width

A = x y

substitute 'y' value in above A = x (40 - x)

A = 40 x - x^2 .....(1)

Step :2

now differentiating equation (1) with respective to 'x'

$\frac{dA}{dx} = 40 -2x$ ........(2)

Find the dimensions

$\frac{dA}{dx} = 0$

40 - 2x =0

40 = 2x

x = 20

and y = 40 - x = 40 -20 =20

The dimensions are x =20 and y=20

length = 20 and breadth = 20

Step 3:-

we have to find maximum area

Again differentiating equation (2) with respective to 'x' we get

$\frac{d^2A}{dx^2} = -2$

Now the maximum area A = x y at x =20 and y=20

A = 20 X 20 = 400

Conclusion:-

The dimensions are x =20 and y=20 of the garden that will maximize its area is 400

verification:-

The perimeter = 2(x +y) =80

2(20 +20) =80

2(40) =80

80 =80

8 0

3 years ago

Use compatible numbers to estimate the quotient 5,514÷82

Sphinxa [80]

The answer is 67 because 67 x 82 is 5,494 which us close to 5,514

5 0

3 years ago

Read 2 more answers