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3 years ago

Prove that 3(x+1)(x+7)-(2x+5)² is never positive

Mathematics

2 answers:

scZoUnD [109]3 years ago

3 0

Step-by-step explanation:

3(x + 1)(x + 7) − (2x + 5)²

3(x² + 8x + 7) − (4x² + 20x + 25)

3x² + 24x + 21 − 4x² − 20x − 25

-x² + 4x − 4

-(x² − 4x + 4)

-(x − 2)²

A squared number is never negative (provided x is a real number), so -(x − 2)² is never positive.

Reika [66]3 years ago

3 0

Answer:

-27x - 219

Step-by-step explanation:

3x+3 * 3x+21 - 6x+15

9x+6 - (6x+15 * 6x+15)

9x+6 - 36x+325

-27x - 219

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3 years ago

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7 0

3 years ago

I need someone to help me do this, see attached documents for the questions

Brilliant_brown [7]

Answer:

1.) 20.2

Step-by-step explanation:

1.) You need to use the distance formula:

$d=\sqrt{(x_{2}-x_{1})^2+(y_{2}-y_{1})^2}$

Find the distance of A to B first:

$(-2,2)(3,2)\\\\\sqrt{(3+2)^2+(2-2)^2}\\\\\sqrt{(5)^2+(0)^2}\\\\\sqrt{25} =5$

B to C:

$(3,2)(-1,-5)\\\\\sqrt{(-1-3)^2+(-5-2)^2}\\\\\sqrt{(-4)^2+(-7)^2}\\\\\sqrt{16+49}\\\\\sqrt{65} =8.06=8.1$

C to A:

$(-1,-5)(-2,2)\\\\\sqrt{(-2+1)^2+(2+5)^2}\\\\\sqrt{(-1)^2+(7)^2}\\\\\sqrt{1+49}\\\\\sqrt{50}=7.07=7.1$

Add distances to find the perimeter:

$5+8.1+7.1=20.2$

2.) Part A:

You need to use the mid-point formula:

$midpoint=(\frac{x_{1}+x_{2}}{2} ,\frac{y_{1}+y_{2}}{2} )$

$(3,2)(7,11)\\\\(\frac{3+7}{2},\frac{2+11}{2})\\\\(\frac{10}{2},\frac{13}{2})\\\\m=( 5,6.5)$

Part B:

1. Use the slope-intercept formula:

$y=mx+b$

M as the slope, b the y-intercept.

Find the slope of the two points A and B using the slope formula:

$m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}} =\frac{rise}{run}$

Insert slope as m into equation.

Take point A as coordinates $(x,y)$ and insert into the equation. Solve for the intercept, b:

$(y)=m(x)+b$

Insert the value of b into the equation.

2. Use the mid-point coordinate. Take the slope.

If you need to find the perpendicular bisector, you will take the negative reciprocal of the slope. Switch the sign and flip it. Ex:

$\frac{1}{2} =-\frac{2}{1}=-2\\$

Insert the new slope into the slope-intercept equation as m.

Take the mid-point coordinate as (x,y) and insert into the equation with the new points. Solve for b.

Insert the value of b.

4 0

3 years ago