Answer:
(5, 3 ) and (- 
, - 10 )
Step-by-step explanation:
Given the 2 equations
2x - y = 7 → (1)
xy = 15 → (2)
Rearrange (1) expressing y in terms of x , that is
y = 2x - 7 → (3)
Substitute y = 2x - 7 into (2)
x(2x - 7) = 15
2x² - 7x = 15 ( subtract 15 from both sides )
2x² - 7x - 15 = 0 ← in standard form
(x - 5)(2x + 3) = 0 ← in factored form
Equate each factor to zero and solve for x
x - 5 = 0 ⇒ x = 5
2x + 3 = 0 ⇒ 2x = - 3 ⇒ x = -
Substitute these values into (3) for corresponding values of y
x = 5 : y = 2(5) - 7 = 10 - 7 = 3 ⇒ (5, 3 )
x = - : y = 2(- ) - 7 = - 3 - 7 = - 10 ⇒ (- , - 10 )
Answer:
70 dolls
Step-by-step explanation:
Hello!
The ratio is 5:2, which are division of a whole. They can be represented as 5x and 2x.
Jacky has 5x dolls, and Peter has 2x dolls. They were equal after subtracting 15 dolls from 5x and adding them to 2x.
Equation:
Solve:
- 5x - 15 = 2x + 15
- 5x - 30 = 2x
- 5x = 2x + 30
- 3x = 30
- x = 10
So Jacky has 5(10) dolls, or 50 dolls, and Peter has 2(10) or 20 dolls.
The total sum is 70 dolls.
Hello from MrBillDoesMath!
Answer:
5 x^3 + 15 x^2 + 15 x + 5 , none of the provided choices
Discussion:
f(x) = 5 x^3
g(x) = x+ 1
=>
(f•g)(x) =
f(g(x)) =
f(x+1) =
5 * (x+1)^3 =
5 x^3 + 15 x^2 + 15 x + 5
which is none of the provided answers.
Thank you,
MrB
9514 1404 393
Answer:
6
Step-by-step explanation:
If 60% are yellow, the other 40% are green. Then the difference between yellow and green is 60% -40% = 20% of the total number of fish. That difference also happens to be half of the number of green fish:
20% = (1/2)(40%)
So, the number of green fish is 2×3 = 6.
_____
If you wanted to, you could write a couple of equations:
y - g = 3
y = 0.60(y +g)
Using the first equation to write an expression for y, we get ...
y = g +3
Using this in the second equation, we have ...
g +3 = 0.6(g +3 +g)
g +3 = 1.2g +1.8 . . . . eliminate parentheses
1.2 = 0.2g . . . . . . . . subtract g+1.8
1.2/0.2 = g = 6 . . . . . divide by 0.2
There are 6 green fish in the aquarium.
