81
(-9)(-9) is 81
Multiplying two negatives gives a positive
2(x+y)=24
2x=y
Use substitution. If y=2x, than we can substitute 2x for it in the other equation, because x and y equal the same things in both equations.
So using that we get 2(x+2x)=24
SIMPLIFY
2(3x)=24
DISTRIBUTE
6x=24.
DIVIDE: x=4.
If we substitute x into the original equations we get x=4 and y=8. Those are your two numbers.
Have a nice day! :)
Answer: x=15
Step-by-step explanation:
Equation: 107=(9x-115)+(4x+27)
Step 1: 9x+4x-115+27=107
Step 2: 13x-115+27=107
Step 3: 13x-88=107
Step 4: 13x-88+88=107+88
Step 5: 13x=195
Step 6: 13x/13=195/13
x=15
When there is a - in front of an expression in parentheses, change the sign of each term in the expression to +
Calculate the LCM of denominators
Calculate the difference
Because the vertex of the parabola is at (16,0), its equation is of the formy = a(x-10)² + 15
The graph goes through (0,0), thereforea(0 - 10)² + 15 = 0100a = -15a = -0.15
The equation is y = f(x) = -0.15(x - 10)² + 15
The graph is shown below.
Part A
Note that y = f(x).
The x-intercepts identify values where the function or y=0. The x-intercepts occur at x=0 and x=20, or at (0,0) and (20,0).
The maximum value of y occurs at the vertex (10, 15) because the curve is down due to the negative leading coefficient of -0.15.
The curve increases in the interval x = (-∞, 10) and it decreases in the interval x = (10, ∞).
Part B
When x=12, y = -0.15(12 - 10)² + 15 = 14.4When x=15, y = -0.15(15 - 10)² + 15 = 11.25
The average rate of change between x =12 to x = 15 is(11.25 - 14.4)/(15 - 12) = -1.05
This rate of change represents the slope of the secant line from A to B. It approximates the rate at which f(x) decreases in the interval x =[12, 15].
