
Solve the following using Substitution method
2x – 5y = -13
3x + 4y = 15


- To solve a pair of equations using substitution, first solve one of the equations for one of the variables. Then substitute the result for that variable in the other equation.

- Choose one of the equations and solve it for x by isolating x on the left-hand side of the equal sign. I'm choosing the 1st equation for now.

- Add 5y to both sides of the equation.


- Multiply
times 5y - 13.

- Substitute
for x in the other equation, 3x + 4y = 15.

- Multiply 3 times
.

- Add
to 4y.

- Add
to both sides of the equation.

- Divide both sides of the equation by 23/2, which is the same as multiplying both sides by the reciprocal of the fraction.

- Substitute 3 for y in
. Because the resulting equation contains only one variable, you can solve for x directly.


- Add
to
by finding a common denominator and adding the numerators. Then reduce the fraction to its lowest terms if possible.

- The system is now solved. The value of x & y will be 1 & 3 respectively.

Let's subtract then: 3x2 - 2x + 3 - (6x2 - 4x + 3)
taking out of the bracket with a changed sign: (there is a minus in front of the bracket)
3x2 - 2x + 3 - 6x2 + 4x - 3
let's reshuffle them so that similar terms are together:
3x2 - 6x2 - 2x + 4x + 3 - 3
Adding up similar terms:
-3x2 + 2x - that's our option 2!
There correct answer is B!
Answers with Explanation.
i. If we raise a number to an exponent of 1, we get the same number.

ii. If we raise 10 to an exponent of 2, it means we multiply 10 by itself two times.

iii. If we raise 10 to an exponent of 3, it means we multiply 10 by itself three times.

iv. If we raise 10 to an exponent of 4, it means we multiply 10 by itself four times.

v. If we raise 10 to an exponent of 5, it means we multiply 10 by itself five times.


vi. Recall that,

We apply this law of exponents to obtain,

vii. We apply

again to obtain,
Volume (V) is (=) Length (L) times (x) Width (W) times (x) Height (H) so V = L x V x H.
Add the variables to the equation.
V = 24 x 10 x 13
Solve
V = 3120
So the volume of the gift box is 3120 cm