Homework Help: Algebra (check answers)

Posted by Stacie on Monday, April 27, 2009 at 5:59pm.

Could you please check my answers we are using substitution to solve each system of equations. And at the end of every solution you are supposed to have an answer as a coordinate.

1. x=2y
x+y=3
Answer (1,2)

2. 2y=3
x-y=10
Answer: (10,10)

3. y=x+7
x+2y= -21
Answer: (-3,-4)

4. 2y=x
x-y=10
Answer: (6,1)

5. x+y=0
4x+4y=0
Answer: (0,0)

6. 2x-y=6
3x-5y=9
Answer: (3,0)

7. 4x-y= -6
y+2=x
Answer: (-8,30)

8. 4x-y= -3
Answer: (3,-6)

9. x-5y=11
3x+y=7
Answer: infinitely many

10. x-2y=5
3x-5y=8
Answer: (-1.75, -8.5)

11. Laura and Ji- Yong were jogging on a 10 mile path. Laura had a 2-mile head start on Ju- Yong. If Laura ran at an average rate of 5 miles per hour and Ji-Yong ran at an average rate of 8 miles per hour, how long would it take for Ji-Yong to catch up with Laura.
Answer: 4 miles.

Algebra (check answers) - Reiny, Monday, April 27, 2009 at 6:23pm
none of your equation answers are correct.

I will #3 for you then follow the same method to do the rest

3. y=x+7
x+2y= -21

sub the first into the second:
x + 2(x+7) = -21
x + 2x + 14 = -21
3x = -35
x = -35/3
now sub that back into the first
y = -35/3 + 7 = -35/3 + 21/3 = -14/3

check:
in #1
LS = y = -14/3
RS = x+7 = -35/3 + 7 = -14/3

in #2
LS = x+2y = -35/3 + 2(-14/3) = -21
RS = -21

now work each one out the same way, and check your answer the same way.
Please someone check this - Stacie, Monday, April 27, 2009 at 6:23pm
If you know how to do this substitution let me know but if you don't that's okay. Also, the last one I redid I got 52:30
Algebra (check answers) - terri, Thursday, May 14, 2009 at 10:03am
x-2y=-1 -x+5y=4 x=-1 y=1

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