Jake’s family traveled a total of 1,543 miles
Answer:
![x = 1](https://tex.z-dn.net/?f=x%20%3D%201)
![y = -3](https://tex.z-dn.net/?f=y%20%3D%20-3)
Step-by-step explanation:
Given :
........................... equation 1
........................... equation 2
solving by substitution method , substitute
into equation 1 , that is
![7x + 3 (-3x ) = -2](https://tex.z-dn.net/?f=7x%20%2B%203%20%28-3x%20%29%20%3D%20-2)
![7x - 9x = - 2](https://tex.z-dn.net/?f=7x%20-%209x%20%3D%20-%202)
![-2x = -2](https://tex.z-dn.net/?f=-2x%20%3D%20-2)
![x = 1](https://tex.z-dn.net/?f=x%20%3D%201)
substitute
into equation 2 to find the value of y , that is
![y = -3 ( 1 )](https://tex.z-dn.net/?f=y%20%3D%20-3%20%28%201%20%29)
![y = -3](https://tex.z-dn.net/?f=y%20%3D%20-3)
The quadratic formula is -b +/-sqrt(b^2-4ac) all over 2a.
First we have to get all the variables on one side so... Subtract 4x: 0=-4x^(2)+13x-3
OR add 3 and subtract 13x: 4x^(2)-13x+3=0
Since I prefer a to be positive, I'm going to choose the second equation.
So... now we just plug and chug. a is the value of the variable squared. In this case a=4. b is the value with the variable, or b=-13. c is the last term. c=3
**Remember: Ax^(2)+By+C**
Now we just plug everything in.
-b= 13 (negative minus a negative is a positive)
+/-sqrt((-13)^(2)-4(4)(3))
all over 2(4)
So work with the radical first.
(-13)^2=169
4(4)(3)=48
+/-sqrt(169-48)
+-sqrt(121)
sqrt(121)=11
Now it's just: (13+/-11)/2(4)
(13+/-11)/8
Split this into two equations:
(13+11)/8
(13-11)/8
Solve both: 24/8=3
2/8=1/4
So x= 3, 1/4
Plug them back in and see if there's one solution or two:
4(3)^2=13(3)-3
36=36
So x=3.
How about 1/4?:
4(1/4)^2=13(1/4)-3
4(1/16)=13/4-3
4/16=13/4-3
1/4=13/4-3
1/4=13/4-(3x4)/(1x4) *Like denominators to add or subtract*
1/4=13/4-12/4
1/4=1/4.
So x=1/4.
In this case, both answers work. So the answer, using the quadratic formula is x=1/4, x=3
Larry will be 35 and his sister will be 28