If 4x-5y = 0, the value of 15y-12x-7 is () a.0 B. - 7 C. - 4 d.7

If 4x-5y = 0, the value of 15y-12x-7 is () a.0 B. - 7 C. - 4 d.7

4x-5y=0
therefore
4x=5y
12x=15y
therefore
15y-12x-7
=0-7
=-7
Choose B

If 4x-5y = 0 and Y ≠ 0, then the value of 12x − 5y12x + 5Y ()
A. 512b. 125C. 12D. Not sure

∵ 4x-5y = 0, ∵ 4x = 5Y, ∵ 12x − 5y12x + 5Y = 3 × 5Y − 5y3 × 5Y + 5Y = 10y20y = 12

One day, Wang Qiang said to Zhang Tao: "I found that 5 can be equal to 4. Here is an equation: 5x-8 = 4x-8, adding 8 on both sides of the equation will get 5x = 4x, dividing x on both sides of the equation will get 5 = 4." please think about it. Is Wang Qiang right? Please give a brief explanation

Reason: the solution of ∵ 5x-8 = 4x-8 is x = 0. When both sides of 5x = 4x are divided by X, that is, both sides are divided by 0, which is wrong

Decompose the following into the factor 4x ^ n + 3-12x ^ n + 2 + 9x ^ n + 1

4x^(n+3)-12x^(n+2)+9x^(n+1)
=x^(n+1)*(4x^2-12x+9)
=x^(n+1)*(2x-3)^2.