How can I not understand the fractional equation 480 / X - 600 / 2x = 45? This is an example in the textbook. The second step is to multiply by the simplest common denominator 2x. I know, but when I go to the denominator, why does the third step become 960-600 = 90x instead of 960-1200 = 90x? Why does 600 not multiply? And why do 480 and 600 go to the denominator without x? I'm going to have an exam tomorrow!

How can I not understand the fractional equation 480 / X - 600 / 2x = 45? This is an example in the textbook. The second step is to multiply by the simplest common denominator 2x. I know, but when I go to the denominator, why does the third step become 960-600 = 90x instead of 960-1200 = 90x? Why does 600 not multiply? And why do 480 and 600 go to the denominator without x? I'm going to have an exam tomorrow!

At the same time, multiply by 2x to get: 960-600 = 90x
90x=360
x=4

Solution equation: (2x ^ 2 + x) ^ 2-2 (2x ^ 2 + x) = 3

A:
（2x^2+x）^2-2（2x^2+x）=3
(2x^2+x)^2-2(2x^2+x)-3=0
(2x^2+x-3)(2x^2+x+1)=0
Because: 2x ^ 2 + X + 1 > 0 is always true (discriminant = 1 ^ 2-4 * 2 * 1 = - 7)

2x-30 = x + 30 solve the equation, fast

Solving equation 180-x = 2x-30

Transference
2x+x=180+30
3x=210
x=210÷3
x=70