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2 years ago

How do I solve these systems of equations?

Mathematics

1 answer:

ruslelena [56]2 years ago

6 0

1. -x+9y=-5
x-5y=1
-----------------
x=1+5y
-(1+5y)+9y=-5
-1-5y+9y=-5
-1+4y=-5
4y=-5-(-1)
4y=-5+1=-4
4y=-4
y=-4/4=-1
So x=1+5y=1+5(-1)=1-5=-4
Answer: x=-4, y=-1. (-4, -1).

2) -7x-y=13
8x+y=-14
------------------
y=-14-8x
-7x-(-14-8x)=13
-7x+14+8x=13
14+x=13
x=13-14=-1
y=-14-8(-1)=-14+8=-6.
Answer: x=-1, y=-6. (-1, -6).

3) x+7y=24
x-9y=-24
----------------
x=24-7y
24-7y-9y=-24
24-16y=-24
16y=24-(-24)=24+24=48
y=48/16=3
x=24-7(3)=24-21=3
Answer: x=3, y=3. (3, 3).

4). 3x+y=-21
x+y=-5
-------------------
x=-5-y
3(-5-y)+y=-21
-15-3y+y=-21
-15-2y=-21
2y=-15-(-21)=-15+21=6
y=6/2=3
x=-5-3=-8.
Answer: x=-8, y=3. (-8, 3).

5) 3x+6y=6
9x-12y=18
---------------
Simplify 3x+6y=6 will get you x+2y=2,
x=2-2y,
9(2-2y)-12y=18
18-18y-12y=18
18-30y=18
30y=18-18=0
y=0/30=0
x=2-2(0)=2-0=2
Answer: x=2, y=0. (2, 0).

6) 6x+8y=26
-7x+2y=-19
-----------------
-4(-7x+2y)=-4(-19)
28x-8y=76
---------------------------
6x+8y=26
28x-8y=76
-----------------
34x=102
x=102/34=3
6(3)+8y=26
18+8y=26
8y=26-18=8
y=8/8=1
Answer: x=3, y=1. (3, 1)

BONUS:
-5x+5y=-25
3x+2y=10
---------------
Simplify -5x+5y=-25 you will get x-y=5
x=y+5
3(y+5)+2y=10
3y+15+2y=10
5y+15=10
5y=10-15=-5
y=-5/5=-1
x=-1+5=4
Answer: x=4, y=-1. (4, -1).

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Answer:

D. is the correct answer

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3 years ago

Read 2 more answers

PLS HELP WILL GIVE BRAINLIEST :)

Rus_ich [418]

Step-by-step explanation:

the slope intercept form is

y = ax + b

"a" being the slope, "b" being the y- intercept (which is the y-value when x = 0).

the slope here :

in the table x is always increasing by 2.

and y is always investing by 1.

so, the slope is 1/2

the y-intercept :

we need to find the y-value for x = 0.

but we don't have a data point with x = 0 in the table.

so, we have to extend the structure of the table to the left.

x decreases by 2 (making it 0), and y decreases by 1 (making it -1).

therefore, the y- intercept (b) is -1.

and the line equation is

y = (1/2)x - 1

not sure about "the other method".

there is the point-slope form of the equation :

y - y1 = a(x - x1)

again with "a" begin the slope, and (x1, y1) being a point on the line.

if we get the y-intercept in the table, then this point is (0, y1).

and the equation would be

y - y1 = ax

in our case

y + 1 = (1/2)x

and another method ?

sometimes people write

nx + my = c

in our case starting with the original equation

y = (1/2)x - 1

2y = x - 2

-x + 2y = -2

x - 2y = 2

6 0

2 years ago

Ax over b plus cx over d equals e solve for x

Lorico [155]

$\frac{ax}{b}+\frac{x}{d}=e\ \ \ \ \ \ |multiply\ both\ sides\ by\ "bd"\\\\bd\times\frac{ax}{b}+bd\times\frac{cx}{d}=bde\\\\adx+bcx=bde\\\\(ad+bc)x=bde\ \ \ \ \ |divide\ both\ sides\ by\ (ad+bc)\\\\\boxed{x=\frac{bde}{ad+bc}}$