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:
Is this the exact persson and question I refused to do?
Step-by-step explanation:
I need the equation to answer the question. manly because I am missing a lot of the question.
Answer: She would require 16 ml cover 240cm^2 of her skin
Step-by-step explanation:
Let m represent the milliliters of sunscreen required to cover her skin.
Let a represent the area of her skin that was covered. She assumes the the relationship between milliliters of sunscreen and the area is proportional. Introducing the constant of variation, k, the expression becomes
m = ka
She uses 3 ml to cover 45cm^2 of her skin. Therefore,
3 = k × 45
k = 3/45 = 1/15
The expression becomes
m = a/15
The milliliters of sunscreen that Kelsey needs to cover 240cm to the power of 2 of her skin would be
m = 240/15
m = 16 ml
Answer:
17/15
Step-by-step explanation:
