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2 years ago

If 3x + 9y = 21 , find the value of 4(x + 3y)

Mathematics

1 answer:

mr Goodwill [35]2 years ago

7 0

Answer:

Step-by-step explanation:

The method that should be used is substitution:

Do this by taking 3x+9y=21 and transforming it to be $y=-\frac{1}{2} x+\frac{7}{3}$

Once you have this, substitute the value of y that we just found into 3x+9y=21 to find the value of x: $3x+9(-\frac{1}{2} +\frac{7}{3} ) =21$

Solve for x. You should get 1.5

Once you have this, Plug in 1.5 for the value of x into the y= equation that we found in the beginning: $y=-\frac{1}{2} (1.5)+\frac{7}{3}$

Solve for y. You should get 1.583 (19/12)

Plug in the values of x and y that we found into the last equation to find its value: 4(1.5+3(1.583))

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If you are reading this please help!!!!

Soloha48 [4]

Given:

$1. -3 x^{2}\left(4 x^{3}-7\right)\\$2. $(6 x-5)(2 x+3)$\\3. $(3 x-1)\left(x^{2}+5 x-2\right)$$

To find:

The product of the polynomials.

Solution:

1. $-3 x^{2}\left(4 x^{3}-7\right)$ $=-3 x^{2}(4 x^{3}) -3 x^{2}(-7)$

Multiply the numerical coefficient and add the powers of x.

$=-12 x^{5}+21 x^{2}$

2. $(6 x-5)(2 x+3)=6 x(2 x+3)-5(2x+3)$

Multiply each term of first polynomial with each term of 2nd polynomial.

Multiply the numerical coefficient and add the powers of x.

$=12 x^2+18x-10 x-15$

$=12 x^2+8x-15$

3. $(3 x-1)\left(x^{2}+5 x-2\right)=3 x(x^{2}+5 x-2)-1(x^{2}+5 x-2)$

Multiply each term of first polynomial with each term of 2nd polynomial.

Multiply the numerical coefficient and add the powers of x.

$=3x^{3}+15 x^2-6x-x^{2}-5 x+2$

Add or subtract like terms together.

$=3x^{3}+14 x^2-11x+2$

The answer for multiplying polynomials:

$1. -12 x^{5}+21 x^{2}$

$2. \ 12 x^2+8x-15$

$3. \ 3x^{3}+14 x^2-11x+2$

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3 years ago

Find the distance between points M(-1,-10) and (-12,-3). round to the nearest tenth

Kitty [74]

The formula of the distance between two points:

$d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}$

We have the points (-1, -10) and (-12, -3). Substitute:

$d=\sqrt{(-12-(-1))^2+(-3-(-10))^2}=\sqrt{(-11)^2+7^2}=\sqrt{121+49}=\sqrt{170}$

$\sqrt{170}\approx13.04$

Answer: d ≈ 13.0

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