Đáp án:
Giải thích các bước giải:
Bài 1.
`a)3-(17-x)=289-(36+289)`
`->3-17+x=289-325`
`->-14+x=-36`
`->x=-36+14`
`->x=-22`
Vậy `x=-22`
`b)34+(21-x)=(3747-30)-3746`
`->34+21-x=-30`
`->55-x=-30`
`->x=55-(-30)`
`->x=85`
Vậy `x=85`
`c)y+25=-63-(-17)`
`->y+25=-46`
`->y=-71`
Vậy `y=-71`
`d)y+20=95-75`
`->y+20=20`
`->y=0`
Vậy `y=0`
`e)(x-2)(x+1)=0`
`->` \(\left[ \begin{array}{l}x-2=0\\x+1=0\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=2\\x=-1\end{array} \right.\)
Vậy `x∈{2;-1}`
`f)(x^2+7)(x^2-9)=0`
Vì `x^2+7≥7->x^2-9=0`
`->x^2=9`
`->x^2=3^2`
`->` \(\left[ \begin{array}{l}x=3\\x=-3\end{array} \right.\)
Vậy `x∈{3;-3}`
`g)24+5x=7^5:7^3`
`->24+5x=7^2`
`->5x=49-24`
`->5x=25`
`->x=5`
Vậy `x=5`
`h)12(x-1):3=4^3+2^3`
`->12(x-1):3=72`
`->12(x-1)=216`
`->x-1=18`
`->x=19`
Vậy `x=19`
