Found 3 solutions by ewatrrr, ikleyn, MathTherapy:
Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!
Hi
y = 3x + 7
y = -4x + 21
solving this System of Equations:
y -3x = 7
y + 4x = 21 |Multiplying the 1st EQ by -1 to eliminate y
-y + 3x = -7
y + 4x = 21
7x = 14
x = 2 and we know y = 3x + 7 y = 13
Ordered Pair P(2,13) is the solution for this system of Equations
Wish You the Best in your Studies.
Sketching the two Lines and showing their Intersection
y = 3x + 7 (Green) y = -4x + 21 (Blue) Note it slants to the left(negative slope)
Answer by ikleyn(52803) (Show Source): You can put this solution on YOUR website!
.
When I see a system of equations like this one, I have ready and I use my standard mantra. It says:
The two given equations have identical left sides - - - hence, their right sides are equal
3x + 7 = -4x + 21.
From this equation
3x + 4x = 21 - 7
7x = 14
x = 14/7 = 2.
Then y = 3x + 7 = 3*2 + 7 = 6 + 7 = 13.
ANSWER. x= 2, y= 13.
Solved.
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My mantra is short and makes the solution short - - - THEREFORE, I like it (!)
You may use it, too (!)
Answer by MathTherapy(10552) (Show Source): You can put this solution on YOUR website!
y = 3x + 7
y = -4x + 21
y = 3x + 7 ----- eq (i)
y = - 4x + 21 ---- eq (ii)
0 = 7x - 14 ------ Subtracting eq (ii) from eq (i)
14 = 7x
Now you can find y.
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