The sum of the angles of a triangle is 180°. So you can do:
91° + (8x + 3)° + (10x - 4)° = 180° To find x, you need to isolate/get the variable "x" by itself in the equation. First combine like terms (terms that have the same variable and power/exponent]
91 + 3 - 4 + 8x + 10x = 180 (I rearranged for the like terms to be next to each other)
90 + 18x = 180 Subtract 90 on both sides
18x = 90 Divide 18 on both sides to get "x" by itself
x = 5
PROOF
91° + (8x + 3)° + (10x - 4)° = 180° Plug in 5 for "x"
91° + (8(5) + 3)° + (10(5) - 4)° = 180°
91° + (40 + 3)° + (50 - 4)° = 180°
91° + 43° + 46° = 180°
180° = 180°
Given:
First term of an arithmetic sequence is 2.
Sum of first 15 terms = 292.5
To find:
The common difference.
Solution:
We have,
First term: 
Sum of first 15 terms: 
The formula of sum of first n terms of an AP is
![S_n=\dfrac{n}{2}[2a+(n-1)d]](https://tex.z-dn.net/?f=S_n%3D%5Cdfrac%7Bn%7D%7B2%7D%5B2a%2B%28n-1%29d%5D)
Where, a is first term and d is common difference.
Putting , n=15 and a=2 in the above formula, we get
![292.5=\dfrac{15}{2}[2(2)+(15-1)d]](https://tex.z-dn.net/?f=292.5%3D%5Cdfrac%7B15%7D%7B2%7D%5B2%282%29%2B%2815-1%29d%5D)
![292.5=\dfrac{15}{2}[4+14d]](https://tex.z-dn.net/?f=292.5%3D%5Cdfrac%7B15%7D%7B2%7D%5B4%2B14d%5D)
![292.5=15[2+7d]](https://tex.z-dn.net/?f=292.5%3D15%5B2%2B7d%5D)
Divide both sides by 15.
Dividing both sides by 7, we get
Therefore, the common difference is 2.5.
To solve, we will follow the steps below:
3x+y=11 --------------------------(1)
5x-y=21 ------------------------------(2)
since y have the same coefficient, we can eliminate it directly by adding equation (1) and (2)
adding equation (1) and (2) will result;
8x =32
divide both-side of the equation by 8
x = 4
We move on to eliminate x and then solve for y
To eliminate x, we have to make sure the coefficient of the two equations are the same.
We can achieve this by multiplying through equation (1) by 5 and equation (2) by 3
The result will be;
15x + 5y = 55 ----------------------------(3)
15x - 3y =63 --------------------------------(4)
subtract equation (4) from equation(3)
8y = -8
divide both-side of the equation by 8
y = -1
Hey,
We can see here 2 of the angles are equal and the third one is a right angle right?
That means it is an isosceles triangle since they have 2 equel angles and a right anlgle.
Another feature of the isosceles triangle is that 2 sides are equal.
We are given one side is 5.5 right?
So the side BC has to be 5.5 or the side AB has to be 5.5
In isosceles triangles the side opposite to the 90 degree angle is the hypotenuse.This means it is the longest angle.
So it has to be AB which is equal to 5.5 since BC is the hypotenuse.
Hope this helps,Happy New Year
Answer:
Step-by-step explanation:
1/2x - 2/3 × 15 = 30
1/2x - 10 = 30
1/2x = 30 + 10
1/2x = 40
x = 40 × 2
x = 80
hope this helps
plz mark it bas brainliest!!!!!!!!!
