I think the answer is x2 + 3x -28 and the x2 is x to the POWER of 2
X + y = 20 Substitute
x by 2 y - 4 in x + y = 20 to obtain 2 y •
4 + y = 20 Solve for y to find y = 8 and
x = 2y - 4 = 12
After each hour 60% ( or 0.60) of the drug will be present.
The equation is A = 100(0.6)^t where t = time in hours. (answer)
Answer:
Step-by-step explanation:
The sum of the ages of a Mother and her son is 78 , three years ago the mother is five times as old as the son, what is their present ages?
To solve this , let the age of the mother be x and the age of the son be y , from the first statement :
x + y = 78
Three years ago , the mother will be x- 3 and the son will be y - 3 , from the second statement:
x - 3 = 5 ( y-3)
x- 3 = 5y - 15
x - 5y = -12
The resulting equations are
x + y = 78
x - 5y = -12
This is called a simultaneous linear equation , that means it is a linear equation.
The side of a square is xcm , if the difference between the area and the perimeter is 12 , find the legth of its side.
Interpretation:
The formula for the area of a square is
and the perimeter is 4l , from the question , we have
- 4x = 12
This is not a linear equation , it is simply a quadratic equation , so the situation is non linear