Câu 4. Tìm X
a) X x 17,7 – 7,7 x X = 177
b) 9 x (12 – 2 x X) = 54
c) X x 3,9 + X x 0,1 = 16
d) 1,23 : X – 0,45 : X = 1,5
e) (X – 1/3) x 5/3 = 14/27 – 3/9
l) (12 x 15 – X) x 1/4 = 120 x 1/4 g) 17/5 : X = 34/5 : 4/3
h) X : 4/5 = 25/8 : 5/4
i) (X x 0,25 + 2012) x 2013 = (50 + 2012) x 2013
k) (X – 1/2) x 5/3 = 7/4 – 1/2
Đáp án:
Câu 4
a)X x17,7-7,7x X=177
X x(17,7-7,7)=177
X x10=177
X=177:10
X=17,7
b)9x(12-2x X)=54
12-2x X=54:9
12-2x X=6
2x X=12-6
2x X=6
X=6:2
X=3
c)X x3,9+X x0,1=16
X x(3,9+0,1)=16
X x4=16
X=16:4
X=4
e)(X-1/3)x5/3=14/27-3/9
(X-1/3)x5/3=5/27
X-1/3=5/27:5/3
X-1/3=1/27
X=1/27+1/3
X=10/27
l)(12×15-X)x1/4=120×1/4
(180-X)x1/4=30
180-X=30:1/4
180-X=120
X=180-120
X=60
g)17/5:X=34/5:4/3
17/5:X=51/10
X=17/4:51/10
X=5/3
h)X:4/5=25/8:5/4
X:4/5=5/2
X=5/4×4/5
X=1
i)(X x0,25+2012)x2013=(50+2012)x2013
(X x0,25+2012)x2013=4 150 806
X x0,25+2012=4 150 806:2013
X x0,25+2012=2062
X x0,25=2062-2012
X x0,25=50
X=50:0,25
X=12,5
k)(X-1/2)x5/3=7/4-1/2
(X-1/2)x5/3=5/4
X-1/2=5/4:5/3
X-1/2=3/4
X=3/4+1/2
X=5/4
Hok tốt ._.
a)X x17,7-7,7x X=177
X x(17,7-7,7)=177
X x10=177
X=177:10
X=17,7
b)9x(12-2x X)=54
12-2x X=54:9
12-2x X=6
2x X=12-6
2x X=6
X=6:2
X=3
c)X x3,9+X x0,1=16
X x(3,9+0,1)=16
X x4=16
X=16:4
X=4
e)(X-1/3)x5/3=14/27-3/9
(X-1/3)x5/3=5/27
X-1/3=5/27:5/3
X-1/3=1/27
X=1/27+1/3
X=10/27
l)(12×15-X)x1/4=120×1/4
(180-X)x1/4=30
180-X=30:1/4
180-X=120
X=180-120
X=60
g)17/5:X=34/5:4/3
17/5:X=51/10
X=17/4:51/10
X=5/3
h)X:4/5=25/8:5/4
X:4/5=5/2
X=5/4×4/5
X=1
i)(X x0,25+2012)x2013=(50+2012)x2013
(X x0,25+2012)x2013=4 150 806
X x0,25+2012=4 150 806:2013
X x0,25+2012=2062
X x0,25=2062-2012
X x0,25=50
X=50:0,25
X=12,5
k)(X-1/2)x5/3=7/4-1/2
(X-1/2)x5/3=5/4
X-1/2=5/4:5/3
X-1/2=3/4
X=3/4+1/2
X=5/4
Phù=3 ! Cuối cùng cũng xong, mệt mún chết,30p’ để tính và làm!