Question

[Phan Đức Gia Linh]

Tìm x, y biết:

a) (-12) . (x - 14) + 7 . (3 - x) = 12.15

b) (2x - 8) . ( y - 2) = 0

c) x^2 - 75 = (-50)

d) (2x - 5)^2 - 1 = 0

e) (3y + 6)^3 + 27 = 0

Answer 1

[Tứ Diệp Thảo]

a) (-12) . (x - 14) + 7 . (3 - x) = 12.15

=> -12x + 168 + 21 - 7x = 180

=> -19x = -9

=> x = \(\frac{9}{19}\)

b) (2x - 8) . ( y - 2) = 0

=> \(\left\{\begin{matrix}2x-8=0\\y-2=0\end{matrix}\right.\Rightarrow\left\{\begin{matrix}x=4\\y=2\end{matrix}\right.\)

c) x^2 - 75 = (-50)

=> \(x^2\)=25

=> \(\left[\begin{matrix}x=5\\x=-5\end{matrix}\right.\)

d) (2x - 5)^2 - 1 = 0

=> ( 2x - 5 ) ^2 = 1

=> \(\left[\begin{matrix}2x-5=1\\2x-5=-1\end{matrix}\right.\)

=>\(\left[\begin{matrix}x=3\\x=2\end{matrix}\right.\)

e) (3y + 6)^3 + 27 = 0

=> \(\left(3y+6\right)^3=-27\)

=> 3y + 6 = -3

=> y = -3