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3 years ago

2(x+y) = 61-2y 4x-4 = 18-3y

Mathematics

1 answer:

Naddik [55]3 years ago

4 0

Answer:

x = 8

y = -7

Step-by-step explanation:

This is a system of equations called simultaneous equations. We shall solve it by elimination method Step 1We shall label the equations (1) and (2)−3y−4x=−11.....(1)3y−5x=−61......(2)Step 2Multiply each term in equation (1) by 1 to give equation (3)1(-3y-4x=-11).....(1)-3y-4x=-11....(3)Step 3Multiply each term in equation 2 by -1 to give equation (4)-1(3y−5x=−61)......(2)-3y+5x=61.....(4)Step 4-3y-4x=-11....(3)-3y+5x=61.....(4)Subtract each term in equation (3) from each term in equation (4)-3y-(-3y)+5x-(-4x)=61-(-11)-3y+3y+5x+4x=61+110+9x=729x=72Step 5Divide both sides of the equation by 9, the coefficient of the unknown variable x to find the value of x 9x/9 = 72/9x = 8Step 6Put in x = 8 into equation (2)3y−5x=−61......(2)3y-5(8)=-613y-40=-61Collect like terms by adding 40 to both sides of the equation 3y-40+40=-61+403y=-21Divide both sides by 3, the coefficient of y to find the value of y 3y/3=-21/3y=-7Therefore, the values of x and y that satisfy the equations are 8 and -7 respectively

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If 3,000 bacteria, with a growth constant (k) of 2.8 per hour, are present at the beginning of an experiment, in how many hours

Ivenika [448]

Given:

Initial number of bacteria = 3000

With a growth constant (k) of 2.8 per hour.

To find:

The number of hours it will take to be 15,000 bacteria.

Solution:

Let P(t) be the number of bacteria after t number of hours.

The exponential growth model (continuously) is:

$P(t)=P_0e^{kt}$

Where, $P_0$ is the initial value, k is the growth constant and t is the number of years.

Putting $P(t)=15000,P_0=3000, k=2.8$ in the above formula, we get

$15000=3000e^{2.8t}$

$\dfrac{15000}{3000}=e^{2.8t}$

$5=e^{2.8t}$

Taking ln on both sides, we get

$\ln 5=\ln e^{2.8t}$

$1.609438=2.8t$ $[\because \ln e^x=x]$

$\dfrac{1.609438}{2.8}=t$

$0.574799=t$

$t\approx 0.575$

Therefore, the number of bacteria will be 15,000 after 0.575 hours.

4 0

2 years ago

Joshua need an equal number of notepads and sticky notes. How many packages of each item does Joshua need to buy? Notepads has 5

stepan [7]

4 packs of notepads and 5 packs of sticky notes
Explanation: if he needs the same number of both he needs to find the first number that 4 and 5 both go into. 4 x 5 = 20 so this is the least common multiple

8 0

2 years ago

Read 2 more answers

Write the given trinomial if possible as a square of a binomial or as an expression opposite to a square of a binomial: 15ab-9a^

MrMuchimi

Answer:

$- \bigg(3a - \frac{5}{2} b) \bigg)^{2}$

Step-by-step explanation:

$15ab-9a^2-6 \frac{1}{4} b^2 \\ \\ = 15ab-(3a)^2-\frac{6 \times 4 + 1}{4} b^2 \\ \\ = 15ab-(3a)^2-\frac{24+ 1}{4} b^2 \\ \\ = 15ab-(3a)^2-\frac{25}{4} b^2 \\ \\ = 15ab- (3a)^2- \bigg(\frac{5}{2} b \bigg)^2 \\ \\ = - \{ - 15ab + (3a)^2 + \bigg(\frac{5}{2} b \bigg)^2 \} \\ \\ = - \{ (3a)^2 + \bigg(\frac{5}{2} b \bigg)^2 - 15ab \} \\ \\ = - \bigg(3a - \frac{5}{2} b \bigg)^{2}$