algebra 1 stuff?

Question

Solve for x.

1. x^2 - 7x+ 12= 0 (i don't know if i'm supposed to use the quadratic formula?)


2. 12/x-40 = 2/3

Answer 1

1.) x² - 7x + 12 = 0 >>>You can do trinomial method or cross-multiplication method.
(x - 3)(x - 4) = 0

x - 3 = 0
x = 3

x - 4 = 0
x = 4

Thus x is 3 or 4

2.) 12 / x - 40 = 2 / 3
12 = 2(x - 40) / 3
12 = 2x - 80 / 3
12(3) = 2x - 80
36 = 2x - 80
-2x = -80 - 36
-2x = -116
x = -116 / -2
x = 58

Answer 2

1. x^2 - 7x+ 12= 0
you only use the quadratic formula when you can't figure out the factors with the numbers that are in the equation. you can figure out this one. ask yourself:
what factors of 12 will add up to negative 7? the answer is -3 and -4. so:
(x - 4)(x - 3) = 0
x - 4 = 0
x = 4

x - 3 = 0
x = 3
so, your answers are 3 and 4. just plug them both into the equation and make sure both really do solve for the equation. if one of them doesn't just throw it out. this would be an extraneous solution.


2.
12/x - 40 = 2/3
first, multiply to get rid of the denominators:
36/x - 120 = 2
36 - 120x = 2x
36 = 122x
36/122 = x
0.295 = x

Answer 3

x^2 -- 7x + 12 = 0
=> x^2 -- 3x -- 4x + 12 = 0
=> x(x -- 3) -- 4(x -- 3) = 0
=> (x -- 3)(x -- 4) = 0
giving x = 3, 4.

12/x -- 40 = 2/3
=> 36 -- 12x = 2x => 14x = 36 => x = 18/7

12/(x -- 40) = 2/3
=> 2(x -- 40) = 36
=> x -- 40 = 18
=> x = 58

Answer 4

Question 1
(x - 4) (x - 3) = 0
x = 3 , x = 4

Question 2
Reading this as:-
12 / (x - 40) = 2 / 3
36 = 2x - 80
2x = 116
x = 58

However could be:-
12/x - 40 = 2/3 (which is what you have written)
36 - 120x = 2x
122x = 36
x = 36 / 122
x = 18 / 61

PS Use brackets to avoid confusion and extra work!!!

Answer 5

umm i think its been 2 years since i have taken algebra 2... soo algebra 1 is a lil rusty.. But i believe the first one is the quadratic formula and the second one all you ahve to do is Add 40 to both sides to get 12/x=40.2/3 then you go multilply both sides by x to get 12=40 2/3 x then divide 12 by 40 2/3 to get X


answer should be .3
x=.3
If i get this one wrong. im very sorry But i think this is correct.

Answer 6

1. you could use the quadratic formula if you wanted to. a=1,b=-7 and c=12 and substitute in, but you could also just factor
(x-3)(x-4) and set each equal to zero. so you get x=3 or 4

2. add 40 to both sides
12/x=40 2/3
then muliply by x to get it on the right side, and then divide by 40 2/3 on both sides to get x

Answer 7

1: x^2 = 7x -12
1: x=SQRT(7x - 12)
1: x=3

2: 12/x = 40 2/3
2: 12/x = 122/3
2: 1/x = 122/36
2: x=36/122
2: x=18/61

Answer 8

1. x^2 - 7x + 12=0
(x - 3)(x - 4)=0
x-3=0; x-4=0
x= 3,4

2. have it at a common denominator:
(12-40x)/x=2/3
12-40x=(2x)/3
24-120x=2x
24=122x
x= 12/61

Answer 9

1. you don't have to...
x ^2 - 7x + 12 = 0
(x -3)(x-4) = 0
X = 3 or 4


2. multiply both side by 3x

36 - 120x = 2x
36 = 122x
x = 36/122