2x-y+7whenx= -5andy-2.

Mathematics

1 answer:

Paha777 [63]3 years ago

7 0

Answer:

-1

Step-by-step explanation:

2x-y+7

Let x = -5 and y = -2

2(-5) -(-2) +7

-10 +2 +7

-10 +9

-1

You might be interested in

PLEASE HELP I think is A or D

Natalka [10]

Looking at the angles of the triangles

N=S
M=R
O=T

so MON would be RTS

5 0

3 years ago

A chemist has 200 mL of a 10% sucrose solution. She adds x mL of a 40% sucrose solution. The percent concentration, y, of the fi

user100 [1]

Answer:

The chemist needs to add 400mL of 40% solution.

Step-by-step explanation:

The equation

$y=\frac{0.1(200)+0.4x}{200+x} *100$

gives the percent concentration $y$ of the final mixture, when $x$ mL of the 40% solution are added.

Now we are asked, how many milliliters $x$ of the 40% solution should the chemist add to get final percent concentration $y=30$ ; this is just a matter of solving the equation

$30=\frac{0.1(200)+0.4x}{200+x} *100$

and we solve it the following way:

$30=\frac{0.1(200)+0.4x}{200+x} *100\\\\0.3 =\frac{0.1(200)+0.4x}{200+x}\\\\0.3(200+x)=0.1(200)+0.4x\\\\60+0.3x=20+0.4x\\\\40=0.1x\\\\x=\frac{40}{0.1} \\\\\boxed{x=400\:mL}$