Toán Lớp 5: tìm x:
a, 7/x =3/12
b, x+x .1/4:2/7+x:2/9=255
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Toán Lớp 5: tìm x:
a, 7/x =3/12
b, x+x .1/4:2/7+x:2/9=255
Comments ( 2 )
a, 7/x =3/12
3xx x = 12xx7
3 xx x = 84
x = 84:3
x = 28
b, x+x .1/4:2/7+x:2/9=255
x + x xx 1/4 : 2/7 + x : 2/9 = 255
x + x xx 1/4 xx 7/2 + x xx 9/2 = 255
x xx (1 + 7/8 + 9/2) = 255
x xx 51/8 = 255
x = 255 : 51/8
x = 40
a,Theo đề bài,ta có:
7/x=3/12
= 7/x=1/4
Quy đồng tử mẫu số,ta được:
7/x=7/28
Vậy số cần tìm là 28
b,X+x.1/4:2/7+x:2/9=255
Xx1+Xx1/4×7/2+Xx9/2=255
Xx1+Xx 7/8 +Xx9/2=255
Xx (1+7/8+9/2) =255
Xx (15/8+9/2 ) =255
Xx (15/8+36/8) =255
Xx 51/8 =255
X =255:51/8
X = 40
Cho mk ctlhn nha!
Chúc bạn học tốt!