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3 years ago

Solving systems of equations y=-3x+4 and x=2y+6

Mathematics

1 answer:

lisabon 2012 [21]3 years ago

6 0

Answer:

<h3>Therefore x=2 and y=-2</h3>

Step-by-step explanation:

Given system of equations are

y= -3x+4

⇔3x+y=4 .........(1)

x= 2y+6

⇔x-2y=6...........(2)

Equation (1) ×2 +equation (2)

6x +2y+x-2y =8+6

⇔7x=14

$\Leftrightarrow x= \frac{14}{7}$

⇔x = 2

Putting the value of x in equation (1)

3.2+y=4

⇔y+6=4

⇔y=4-6

⇔y=-2

Therefore x=2 and y=-2

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Write an equation of a parabola that passes through (3,-30) and has x-intercepts of -2 and 18. Then find the average rate of cha

Nookie1986 [14]

Answer:

The equation of the parabola is $y = \frac{2}{5}\cdot x^{2}-\frac{32}{5}\cdot x -\frac{72}{5}$ . The average rate of change of the parabola is -4.

Step-by-step explanation:

We must remember that a parabola is represented by a quadratic function, which can be formed by knowing three different points. A quadratic function is standard form is represented by:

$y = a\cdot x^{2}+b\cdot x + c$

Where:

$x$ - Independent variable, dimensionless.

$y$ - Dependent variable, dimensionless.

$a$ , $b$ , $c$ - Coefficients, dimensionless.

If we know that $(3, -30)$ , $(-2, 0)$ and $(18, 0)$ are part of the parabola, the following linear system of equations is formed:

$9\cdot a +3\cdot b + c = -30$

$4\cdot a -2\cdot b +c = 0$

$324\cdot a +18\cdot b + c = 0$

This system can be solved both by algebraic means (substitution, elimination, equalization, determinant) and by numerical methods. The solution of the linear system is:

$a = \frac{2}{5}$ , $b = -\frac{32}{5}$ , $c = -\frac{72}{5}$ .