Đề bài
Tìm y, biết :
a)y+45%.y=−1,45b)y−25%.y=12.
Lời giải chi tiết
a)y+45%.y=−1,45y+45100y=−145100y+920y=−2920(1+920)y=−2920(2020+920)y=−29202920y=−2920y=−2920:2920⇔y=−1.b)y−25%y=12y−25100y=12y−14y=12(1−14)y=12⇔(44−14)y=1234y=12⇔y=12:34y=12.43⇔y=23
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