Answer:
![x=-3,13](https://tex.z-dn.net/?f=x%3D-3%2C13)
Step-by-step explanation:
Given: ![x^2-10x=39](https://tex.z-dn.net/?f=x%5E2-10x%3D39)
To find: solutions of the given equation
Solution:
![x^2-10x=39\\x^2-10x-39=0](https://tex.z-dn.net/?f=x%5E2-10x%3D39%5C%5Cx%5E2-10x-39%3D0)
Write ![-10=-13+3](https://tex.z-dn.net/?f=-10%3D-13%2B3)
Therefore,
![x^2-13x+3x-39=0\\x(x-13)+3(x-13)=0\\(x+3)(x-13)=0\\x=-3,13](https://tex.z-dn.net/?f=x%5E2-13x%2B3x-39%3D0%5C%5Cx%28x-13%29%2B3%28x-13%29%3D0%5C%5C%28x%2B3%29%28x-13%29%3D0%5C%5Cx%3D-3%2C13)
So, solutions of the given equation are
and
.
Answer: r - 24
Step-by-step explanation:
![X=r+2;Y=2r-9;Z=r^2+17x+30](https://tex.z-dn.net/?f=X%3Dr%2B2%3BY%3D2r-9%3BZ%3Dr%5E2%2B17x%2B30)
![\frac{x*y-z}{x}](https://tex.z-dn.net/?f=%5Cfrac%7Bx%2Ay-z%7D%7Bx%7D)
![\frac{[(r+2)(2r-9)]-(r^2+17r+30)}{r+2}](https://tex.z-dn.net/?f=%5Cfrac%7B%5B%28r%2B2%29%282r-9%29%5D-%28r%5E2%2B17r%2B30%29%7D%7Br%2B2%7D)
![\frac{(2r^2-9r+4r-18)-(r^2+17r+30)}{r+2}](https://tex.z-dn.net/?f=%5Cfrac%7B%282r%5E2-9r%2B4r-18%29-%28r%5E2%2B17r%2B30%29%7D%7Br%2B2%7D)
![\frac{(2r^2-5r-18)-(r^2+17r+30)}{r+2}](https://tex.z-dn.net/?f=%5Cfrac%7B%282r%5E2-5r-18%29-%28r%5E2%2B17r%2B30%29%7D%7Br%2B2%7D)
![\frac{2r^2-5r-18-r^2-17r-30)}{r+2}](https://tex.z-dn.net/?f=%5Cfrac%7B2r%5E2-5r-18-r%5E2-17r-30%29%7D%7Br%2B2%7D)
Combine like terms;
![\frac{r^2-22r-48}{r+2}](https://tex.z-dn.net/?f=%5Cfrac%7Br%5E2-22r-48%7D%7Br%2B2%7D)
Solve the quadratic equation;
![\frac{(r-24)(r+2)}{r+2}](https://tex.z-dn.net/?f=%5Cfrac%7B%28r-24%29%28r%2B2%29%7D%7Br%2B2%7D)
Simplify;
![r-24](https://tex.z-dn.net/?f=r-24)
answer: $11.40
explanation: turn the percent into a decimal, multiply it by the starting cost, then subtract the product from the starting cost
>> 40% = 0.40
0.40 x 19 = 7.60
19 - 7.60 = 11.40
Answer:
10
Step-by-step explanation:
Add the percentage as a decimal
To 1 to get 1.20
Multiply:
340 x 1.20 = 408
Answer: 408