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MeganDarling
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I would really appreciate step by step help on these 2 Algebraic systems ! 1. Solve using substitution . 4.5x2y=12.5 , 3.25xy=0.75.
2.Solve this system using elimination . 5x+4y=12 , 3x3y=18. Thanks! Also help with this would be lovely.. The length of a rectangle is 9.7 cm more than 4 times the width. If the perimeter of the rectangle is 91.4 cm, what are its dimensions?
 2 years ago
 2 years ago
MeganDarling Group Title
I would really appreciate step by step help on these 2 Algebraic systems ! 1. Solve using substitution . 4.5x2y=12.5 , 3.25xy=0.75. 2.Solve this system using elimination . 5x+4y=12 , 3x3y=18. Thanks! Also help with this would be lovely.. The length of a rectangle is 9.7 cm more than 4 times the width. If the perimeter of the rectangle is 91.4 cm, what are its dimensions?
 2 years ago
 2 years ago

This Question is Closed

chipperdrew Group TitleBest ResponseYou've already chosen the best response.2
I'll try to be detailed, let me know if I lose you anywhere. 1. With substitution, our goal is to solve for either 'x' or 'y' in one of our equations, and plug it into the other. So we have: 4.5x2y=12.5 and 3.25xy=0.75 Personally, I would solve the second equation for 'y' because that looks easiest. But it's completely up to you if you want to do something different. 3.25xy=0.75 > y = 3.25x + 0.75 Now plug this back into the second equation: 4.5x2y=12.5 4.5x 2(3.25x + 0.75) = 12.5 4.5x6.5x1.5 = 12.5 11x = 14 x = 14/11 Plug this into what we used to substitute 'y' to find 'y' now. y = 3.25(14/11)+0.75 y = 149/44 2. The goal of elimination is to get either 'y' or 'x' to have the same coefficient out front, one negative and one positive. 5x+4y=12 3x3y=18 I'm going to try to get the same coefficient in front of 'y'. I see that 4*3=12, so I could multiply the top equation by 3 and the bottom on by 4 to get: 15x+12y=36 12x12y=72 Now we can add the two. This gives: 27x = 108 x = 4 If we plug this back into either one of our two original equations, we'll find 'y' also. 5(4)+4y = 12 4y = 8 y = 2 I'll solve your 3rd question in just a second....
 2 years ago

MeganDarling Group TitleBest ResponseYou've already chosen the best response.0
Oh man I feel so dumb x.x I totally screwed you over because the first equation was supposed to be 4.5x2y=12.5 . AH , I am so sorry :/ You were nice enough to help and I think I messed a bunch up ):
 2 years ago

MeganDarling Group TitleBest ResponseYou've already chosen the best response.0
But thanks so much anyways haha, x.x
 2 years ago

chipperdrew Group TitleBest ResponseYou've already chosen the best response.2
The last problem is what makes math fun, in my opinion. We need to turn words into math. Let's look at this sentence by sentence: 'The length of a rectangle is 9.7 cm more than 4 times the width.' What does that tell us? If we let 'L' be length and 'W' be width, we know: L = 9.7+4W Good. Now let's look at the second sentence: 'If the perimeter of the rectangle is 91.4 cm, what are its dimensions?' What does that tell us? What is perimeter? Hopefully we are familiar with P = 2L + 2W, where P is perimeter 91.4 = 2L + 2W We now have 2 equations with 2 unknowns (L,W), so we can solve for length and width. I'll let you choose solve this, I know you're capable of doing so! :) L = 9.7+4W 91.4 = 2L + 2W
 2 years ago

chipperdrew Group TitleBest ResponseYou've already chosen the best response.2
Haha I was a little concerned by the ugly fractions in the first part, I was hoping that your teacher wasn't that mean!
 2 years ago

MeganDarling Group TitleBest ResponseYou've already chosen the best response.0
Aw man he's pretty evil, but unfortunately it was just my mess up x.x So what would I do differently with that 1st equation :o ?
 2 years ago

MeganDarling Group TitleBest ResponseYou've already chosen the best response.0
And so with my last problem I have to solve the solution using either substitution or elimination >.< ?
 2 years ago

MeganDarling Group TitleBest ResponseYou've already chosen the best response.0
Eek, I'm definitely not a math lover x.x But I'll give it my best shot haha
 2 years ago

chipperdrew Group TitleBest ResponseYou've already chosen the best response.2
Yep, both substitution and elimination should work. Choose your favorite. For the first equation, it doesn't change all that much. I would still use the 2nd equation to find 'y' and substitute into the first equation Now plug this back into the second equation: 4.5x2y=12.5 4.5x 2(3.25x + 0.75) = 12.5 4.5x6.5x1.5 = 12.5 11x = 11 x = 1 And plug it back in to find 'y' y = 3.25(1) + 0.75 y = 4 It's always good to plug 'x' and 'y' back into your equations to check your answer also.
 2 years ago

MeganDarling Group TitleBest ResponseYou've already chosen the best response.0
oh phew that worked out alot nicer than my mess up equation did haha (: Thanks
 2 years ago

MeganDarling Group TitleBest ResponseYou've already chosen the best response.0
I dunno which is my favorite haha, both ways are pretty difficult for me :/ I usually just end up messing one little thing up along the way x.x
 2 years ago

chipperdrew Group TitleBest ResponseYou've already chosen the best response.2
Fortunately it will get easier the more you do it. Everyone makes silly math mistakes so don't worry too much about that! There's also a 3rd option to solving the systems equations by graphing it, but I don't want to throw anything else at you!
 2 years ago

MeganDarling Group TitleBest ResponseYou've already chosen the best response.0
Lol I know but I'm even worse at that x.x haha
 2 years ago

MeganDarling Group TitleBest ResponseYou've already chosen the best response.0
Well I will try my best! thank you!
 2 years ago

chipperdrew Group TitleBest ResponseYou've already chosen the best response.2
Best of luck to you!
 2 years ago

Whiterabbit541 Group TitleBest ResponseYou've already chosen the best response.1
3) L = 4W + 9.7 2L + 2W = 91.4 2(4W + 9.7) + 2W = 91.4 8W + 19.4 + 2W = 91.4 10W + 19.4 = 91.4 10W = 72 W = 7.2 L = 4(7.2) + 9.7 L = 28.8 + 9.7 L = 38.5 2(38.5) + 2(7.2) = 91.4 77 + 14.4 = 91.4 91.4 = 91.4 L = 38.5 and W = 7.2
 one year ago
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