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).
Answer:
L = 100
W = 60
Step-by-step explanation:
2L + 2W = 320
-2L + 2W = -80
4W = 240
W = 60
L - W = 40
L - 60 = 40
L = 100
Answer:
27
General Formulas and Concepts:
<u>Pre-Algebra</u>
Order of Operations: BPEMDAS
- Brackets
- Parenthesis
- Exponents
- Multiplication
- Division
- Addition
- Subtraction
Step-by-step explanation:
<u>Step 1: Define</u>
3 - 6(z - 2)
z = -2
<u>Step 2: Evaluate</u>
- Substitute in <em>z</em>: 3 - 6(-2 - 2)
- (Parenthesis) Subtract: 3 - 6(-4)
- Multiply: 3 + 24
- Add: 27
