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3 years ago

3x - 5y+5=04x+ 7y+8=0Please help

Mathematics

1 answer:

natima [27]3 years ago

3 0

Answer:

Y= -4. X=5

Step-by-step explanation:

This is a simultaneous equation

3x+5y= -5 ------------(1)

4x+5y= -8 ------------(2)

Using elimination method

Eliminate x

×4. 3x+5y= -5

×3. 4x+7y= -8

12x+20y= -20

-(12x+21y= -24) Minus

-y=4 therefore y= -4

Substitute x into equation 1

3x+5(-4)= -5

3x-20= -5

3x= -5+20

3x= 15

x=5

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If 180° < α < 270°, cos⁡ α = −817, 270° < β < 360°, and sin⁡ β = −45, what is cos⁡ (α + β)?

eduard

Answer:

$cos(\alpha+\beta)=-\frac{84}{85}$

Step-by-step explanation:

we know that

$cos(\alpha+\beta)=cos(\alpha)*cos(\beta)-sin(\alpha)*sin(\beta)$

Remember the identity

$cos^{2} (x)+sin^2(x)=1$

step 1

Find the value of $sin(\alpha)$

we have that

The angle alpha lie on the III Quadrant

The values of sine and cosine are negative

$cos(\alpha)=-\frac{8}{17}$

Find the value of sine

$cos^{2} (\alpha)+sin^2(\alpha)=1$

substitute

$(-\frac{8}{17})^{2}+sin^2(\alpha)=1$

$sin^2(\alpha)=1-\frac{64}{289}$

$sin^2(\alpha)=\frac{225}{289}$

$sin(\alpha)=-\frac{15}{17}$

step 2

Find the value of $cos(\beta)$

we have that

The angle beta lie on the IV Quadrant

The value of the cosine is positive and the value of the sine is negative

$sin(\beta)=-\frac{4}{5}$

Find the value of cosine

$cos^{2} (\beta)+sin^2(\beta)=1$

substitute

$(-\frac{4}{5})^{2}+cos^2(\beta)=1$

$cos^2(\beta)=1-\frac{16}{25}$

$cos^2(\beta)=\frac{9}{25}$

$cos(\beta)=\frac{3}{5}$

step 3

Find cos⁡ (α + β)

$cos(\alpha+\beta)=cos(\alpha)*cos(\beta)-sin(\alpha)*sin(\beta)$

we have

$cos(\alpha)=-\frac{8}{17}$

$sin(\alpha)=-\frac{15}{17}$

$sin(\beta)=-\frac{4}{5}$

$cos(\beta)=\frac{3}{5}$

substitute

$cos(\alpha+\beta)=-\frac{8}{17}*\frac{3}{5}-(-\frac{15}{17})*(-\frac{4}{5})$

$cos(\alpha+\beta)=-\frac{24}{85}-\frac{60}{85}$

$cos(\alpha+\beta)=-\frac{84}{85}$

4 0

3 years ago

ASAP PLZ!!!

lyudmila [28]

The solution has to be a value of x. Since you already have x, you just have to plug in the value and see what fits. In this case thats the third from the top:

5^2 - 10*5 + 25 = 0

25 - 50 + 25 = 0

0 = 0

Hope it helps!

7 0

3 years ago

Need help with this question, if you don’t know it don’t answer it please

Lerok [7]

Answer:

Step-by-step explanation:

9 x 3 x 2 = 54

7 0

3 years ago

Read 2 more answers

A truck can be rented from Company A form $130 a day plus $0.30 per mile. Company B charges $50 a day plus $0.80 per mile to r

navik [9.2K]

Answer:

160 miles

Step-by-step explanation:

Company A form $130 a day plus $0.30 per mile

Company A = 130 + 0.30x

Company B charges $50 a day plus $0.80 per mile

Company B = 50 + 0.80x

Where,

x = number of miles

Equate the cost of company A and company B

130 + 0.30x = 50 + 0.80x

Collect like terms

130 - 50 = 0.80x - 0.30x

80 = 0.50x

Divide both sides by 0.50x

x = 80 / 0.50

= 160

x = 160 miles

The number of miles in a day at which the rental costs for Company A and Company B are the same is 160 miles

4 0

2 years ago

What is the least common multiple of 441 and 1008

topjm [15]

7056. 1008 x 7 = 7056. 7056 / 441 = 16

4 0

3 years ago

3x - 5y+5=04x+ 7y+8=0Please help ​

3x - 5y+5=04x+ 7y+8=0Please help