If two angles are congruent, then the angles are vertical angles.

Solving a system of equations using substitution requires one side to be equal to a variable present in the equation, in this case x or y. We should simplify the equation using elimination before substituting to reduce the chance of error.

In order to use the elimination method, you have to create variables that have the same coefficient—then you can eliminate them. These equations arew already aligned for us.

3x - 10y=-70

- 4x +9y = 63

-x + y = 7

Now, for substitution, the equation must be set to a variable.

-x + y = 7

y = x + 7

Next, plug the equation in where applicable in another equation.

4x +9(x + 7) = 63

4x + 9x + 63 = 63

13x = 0

x = 0

The final step of substitution is to plug the known variable into an equation to find the other variable.

3(0) - 10y=-70

0 - 10y = -70

10y = 70

y = 7

I guarantee you this answer is correct, I worked it out using other methods and graphing prior to submitting this answer.

8 0

3 years ago

Read 2 more answers

Number 1 and 2 please (25 points)

Elenna [48]

Answers:

1) $(3x+2)+(4-5x)=-2x+6$

$(3+2i)+(4-5i)=7-3i$

2) $(1-3x)(2+x)=-3x^{2}-5x+2$

$(1-3i)+(2+i)=5-5i$

Step-by-step explanation:

In mathematics there are rules related to complex numbers, specifically in the case of addition and multiplication:

Addition:

If we have two complex numbers written in their binomial form, the sum of both will be a complex number whose real part is the sum of the real parts and whose imaginary part is the sum of the imaginary parts (similarly as the sum of two binomials).

For example, the addition of these two binomials is:

$(3x+2)+(4-5x)=3x-5x+2+4=-2x+6$

Similarly, the addition of two complex numbers is:

$(3+2i)+(4-5i)=3+4+2i-5i=7-3i$ Here the complex part is the number with the $i$

Multiplication:

If we have two complex numbers written in their binomial form, the multiplication of both will be the same as the multiplication (product) of two binomials, taking into account that $i^{2}=-1$ .