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3 years ago

How do you solve substitution problems in Pre Algebra

2 answers:

6 0

Get x or y alone in one equation and plug it in for the next. Then save for x/y and plug your answer in to either equation to get the other variable...For Example: 2x+8y=-8 and 4x=-64
4x=-64y
Divide by 4 on each side and get x=-8y
Plug in -8y for x in the other equation and solve for y
2(-8y)+8y=-8
-16y+8y=-8
-8y=-8
y=1
Plug in y to original equation 2x+8y=-8 to find x
2x+8(1)=-8
2x+8=-8
Subtract 8 and get 2x=-16
And solve for x so x=-8
Coordinates: (-8,1)

Rus_ich [418]3 years ago

4 0

You multiply both of the equations until you have two of the same term the same like for example, say I have 4x and 5x. You want to multiply until both have the same number, so multiply 5x by four, then multiply 4x by five, and you will get 20x, then both of those cancel out and you will be left with the other variable, and you just solve like a normal equation.

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Find the slope of the line that is (a) parallel and (b) perpendicular to the line through the pair of points.

ddd [48]

Answer:

a) The slope of the line is parallel to the another line m=4

b) The slope of the line is perpendicular to the another line m= $\frac{-1}{4}$

Step-by-step explanation:

Step1:-

Slope of a line :-

If θ is the inclination of a line 'l' then tanθ is called the slope or gradient of the line 'l'.The slope of a line is denoted by m=tanθ

The slope of a line given two points m= $\frac{y_{2}-y_{1} }{x_{2} -x_{1} }$

Parallel lines:-

Two non-vertical lines are parallel if and only if their slopes are parallel

Perpendicular lines:-

Two non-vertical lines are perpendicular to each other if and only if their slopes are negative reciprocals of each other.

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

Step 2:-

a)The slope of a line when given two points (-1,-4) and (0,0)

$m = \frac{0-(-4)}{0-(-1)} =4$

Two non-vertical lines are parallel if and only if their slopes are parallel

$m_{1} = m_{2}$

Therefore the slope of the line that is parallel to the another line

$m_{1} =m_{2} =4$

Step 3:-

b) Two non-vertical lines are perpendicular to each other if and only if their slopes are negative reciprocals of each other.

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

$m_{2} =\frac{-1}{4}$

Therefore the slope of the line is perpendicular to the another line is

$m=\frac{-1}{4}$

3 0

3 years ago

Read 2 more answers

What is a radius in geometry, and what are some examples of it?

mixer [17]

A radius is a straight line from the centre to the edge of a circle. i’m not sure about any examples sorry :/

6 0

2 years ago

Second Time Asking This:

sattari [20]

128 ÷3=42.66

it doesn't say if they have to pay the money back but if they do it's

128-35= 43

43÷3= 14.33

8 0

2 years ago

This is it guys thx!✨

Tanzania [10]

Answer:

It's D: 16

Step-by-step explanation:

6 0

3 years ago

Please? I need help here

Yuki888 [10]

Answer:

Step-by-step explanation:

If pair of ratios does form a true proportion then:

$a:b=c:d\to\dfrac{a}{b}=\dfrac{c}{d}\to ad=bc$

$A)\\\\8:14=20:35\to\dfrac{8}{14}=\dfrac{20}{35}\\\\(8)(35)=(14)(25)\\\\280=280\qquad\bold{TRUE}\\\\b)\\\\\dfrac{6}{10}=\dfrac{15}{25}\\\\(6)(25)=(10)(15)\\\\150=150\qquad\bold{TRUE}$

$c)\\\\\dfrac{9}{5}=\dfrac{27}{15}\\\\(9)(15)=(5)(27)\\\\135=135\qquad\bold{TRUE}\\\\d)\\\\12:15=30:50\to\dfrac{12}{15}=\dfrac{30}{50}\\\\(12)(50)=(15)(30)\\\\600=450\qquad\bold{FALSE}$

3 0

3 years ago