Their are 2 main methods of solving 2 equations with 2 variables:
1) SUBSTITUTION
2) ELIMINATION
I'll show you both:
1) y = 2x + 160
y = - 3x + 208
plug what y is equal to in 1st equation into the y of the 2nd:
2x + 160 = -3x + 208
2x + 3x + 160 = -3x + 3x + 208
5x + 160 -160 = 208 - 160
5x = 48
5x/5 = 48/5
x = 48/5 = 9 3/5
now plug that x into either one of the original equations: y = -3x + 208 = -3(48/5) + 208
y = -144/5 + 208 = 1040/5 - 144/5 = 896/5
y = 179 1/5
2) add the whole equations together so as to cancel out one of the variables:
I'm choosing to eliminate the y, so we need y-y to remove the y's, I'll multiply the whole 2nd equation by -1 to make that -y
-1 (y = - 3x + 208)
-y = 3x - 208
So set it up like:
y = 2x + 160
-[y = 3x - 208]
---------------------
0 = 5x - 48
0+48 = 5x -48 +48
5x = 48
5x/5 = 48/5
x = 48/5
plug that x value into one of the original equations: y = 2x + 160 = 2(48/5) + 160
y = 96/5 + 160 = 96/5 + 800/5 = 896/5
y = 179 1/5
SO WE GOT THE SAME VALUES BOTH WAYS.
WHEN YOU SEE FUTURE PROBLEMS LIKE THESE, SOME WILL BE QUICKER BY ELIMINATION AND OTHERS BY SUBSTITUTION
Answer:
see below
Step-by-step explanation:
8(n + 2)(n + 4) = 1,144
FOIL
8(n^2 +2n+4n+8) = 1144
Divide each side by 8
8/8(n^2 +2n+4n+8) = 1144/8
(n^2 +2n+4n+8) = 143
Combine like terms
n^2 +6n+8 = 143
Subtract 143 from each side
n^2 +6n+8 -143= 0
Combine like terms
n^2 +6n -135 =0
Factor
What two terms multiply to -135 and add to 6
-9*15 =-135
-9+15 = 6
(n-9) (n+15) =0
Using the zero product property
n-9 =0 n+15=0
n = 9 n=-15
The length cannot be negative so n = -15 cannot be a solution
n =9
the missing number is 1/8 i hope this helps chu
