Đáp án:
Giải thích các bước giải:
Bài 1:
`a)120+(-35).(-4)`
`=120+140=260`
`b)-25.(-111).(-4).9`
`=(-25).(-4).(-111).9`
`=100.(-111).9`
`=-99900`
`c)5.(2-5)^2 + 3.(7-3)^3`
`=5.(-3)^2+3.4^3`
`=5.9+3.64`
`=45+192=237`
Bài 2:
`a)(x-41)+58=10`
`->x-41+58=10`
`->x=10+41-58`
`->x=-7`
Vậy `x=-7`
`b)(-3)|x+7|=-18`
`->|x+7|=6`
`->` \(\left[ \begin{array}{l}x+7=6\\x+7=-6\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=-1\\x=-13\end{array} \right.\)
Vậy `x∈{-1;-13}`
`c)(x-8)(x+9)=0`
`->` \(\left[ \begin{array}{l}x=8\\x=-9\end{array} \right.\)
Vậy `x∈{8;-9}`
Bài 3:
`a)(a-b+c)-(d+c-b)`
`=a-b+c-d-c+b`
`=a+(-b+b)+(c-c)-d`
`=a+2c-d`
`b)-35\vdotsn-8->n-8∈Ư(-35)={±1;±5;±7;±35}`
Ta có bảng:
\begin{array}{|c|c|}\hline n-8&1&-1&5&-5&7&-7&35&-35\\\hline n&9&7&13&3&15&1&43&-27\\\hline\end{array}
Vậy `n∈{9;7;13;3;15;1;43;-27}`