4/ Tìm y
A/ 25,5 + y - 12,5 = 4 x 7
b. 76,22 - y - 25,7 = 30 + 5,52
c. 4,5 - y +1,2 = 3,5
Tìm y:
y x 4,9 + y :10 = 1,2
y x 4,5 - y : 2 = 2,6
y : 10 + y x 3,9 = 6
y x 8,25 - y : 4 = 3
a) y x 4,9 : 10 = 12
y x 49 = 12
y = 12 : 49
y = tự tính
\(y\times4,9+y\div10=1,2\)
\(y\times4,9+y\times\dfrac{1}{10}=1,2\)
\(y\times4,9+y\times0,1=1,2\)
\(y\times\left(4,9+0,1\right)=1,2\)
\(y\times5=1,2\)
\(y=1,2\div5\)
\(y=0,24\)
Tìm y
a) y x 4,5 = 55,8
b) y : 2,5 = 25,42
Tìm y:
Y x 3,5 = 22,19
48,3 - Y x 2,8 = 30,716
Y : 5,7 - 5,6 = 12,5
Lời giải:
$y\times 3,5=22,19$
$y=22,19:3,5=6,34$
----------
$48,3-y\times 2,8=30,716$
$y\times 2,8=48,3-30,716=17,584$
$y=17,584:2,8=6,28$
-----------
$y:5,7-5,6=12,5$
$y:5,7=12,5+5,6=18,1$
$y=18,1\times 5,7=103,17$
Tìm y
A.30,5 : (y -12,5) = 12,2 B. (15,5 + y ) × 4 = 140,56
C.0,5 × y = 10 × 0,2. D. 4,5 : y = 0,85 + 0,35
Làm nhanh cho mik nhé
a.30,5:(y-12,5)=12,2
y-12,5=30,5:12,2
y-12,5=2,5
y=2,5+12,5
y= 15
b.(15,5+y)x4=140,56
15,5+y=140,56:4
15,5+y=35,14
y=35,14-15,5
y=19,64
c.0,5xy=10x0,2
0,5xy=2
y=2:0,5
y=4
d.4,5:y=0,85+0,35
4,5:y=1,2
y=4,5:1,2
y=3,75
học tốt
Tìm các sô nguyên x và y
a, x.y = -7
b, x.( y-1) = -23
c, xy + 3x - 7y = 21
a: \(\left(x,y\right)\in\left\{\left(1;7\right);\left(7;1\right);\left(-1;-7\right);\left(-7;-1\right)\right\}\)
a. X : (28,8 : 4,5)= 50,4 b. 53,2 : (X – 3,5) = 99 - 45,8
c. X x 2,5 x 4= 12,5 d. X – 12,22 : 4,7 = 8,15
MN ƠI GIÚP MIK CÂU NÀY VỚI MIK CẦN RẤT GẤP
AI TRẢ LỜI NHANH NHẤT MIK SẼ CHO NƯỜI ĐÓ 1 LIKE
1.Tính
a.-15,5×20,8+3,5×9,2-15,59,2+3,5×20,8
b. [(-19,95)+(-45,75)]+[4,95+5,75]
2.Tìm x,y biết :
a.2|2x-3|=1
b.7.5-3|5-2x|=-4,5
c.|3x-4|+|3y+5|=0
3.So sánh
a.2^300 và 3^200
b.2^30+3^30+4^30 và 3×2×4^10
2)
a) \(2\left|2x-3\right|=1\)
=> \(\left|2x-3\right|=1:2\)
=> \(\left|2x-3\right|=\frac{1}{2}\)
=> \(\left[{}\begin{matrix}2x-3=\frac{1}{2}\\2x-3=-\frac{1}{2}\end{matrix}\right.\) => \(\left[{}\begin{matrix}2x=\frac{1}{2}+3=\frac{7}{2}\\2x=\left(-\frac{1}{2}\right)+3=\frac{5}{2}\end{matrix}\right.\) => \(\left[{}\begin{matrix}x=\frac{7}{2}:2\\x=\frac{5}{2}:2\end{matrix}\right.\)
=> \(\left[{}\begin{matrix}x=\frac{7}{4}\\x=\frac{5}{4}\end{matrix}\right.\)
Vậy \(x\in\left\{\frac{7}{4};\frac{5}{4}\right\}.\)
b) \(7,5-3\left|5-2x\right|=-4,5\)
=> \(4,5\left|5x-2\right|=-4,5\)
=> \(\left|5x-2\right|=\left(-4,5\right):4,5\)
=> \(\left|5x-2\right|=-1\)
Ta luôn có: \(\left|x\right|>0\forall x\)
=> \(\left|5x-2\right|>-1\)
=> \(\left|5x-2\right|\ne-1\)
Vậy không tồn tại giá trị nào của \(x\) thỏa mãn yêu cầu đề bài.
c) \(\left|3x-4\right|+\left|3y+5\right|=0\)
Ta có: \(\left|3x-4\right|>\) hoặc \(=0\forall x\)
\(\left|3y+5\right|>\) hoặc \(=0\forall y.\)
=> \(\left|3x-4\right|+\left|3y+5\right|=0\)
=> \(\left[{}\begin{matrix}3x-4=0\\3y+5=0\end{matrix}\right.\) => \(\left[{}\begin{matrix}3x=0+4=4\\3y=0-5=-5\end{matrix}\right.\) => \(\left[{}\begin{matrix}x=4:3\\y=\left(-5\right):3\end{matrix}\right.\)
=> \(\left[{}\begin{matrix}x=\frac{4}{3}\\y=-\frac{5}{3}\end{matrix}\right.\)
Vậy \(x\in\left\{\frac{4}{3}\right\};y\in\left\{-\frac{5}{3}\right\}.\)
Chúc bạn học tốt!
Bài 1:
a) \(-15,5.20,8+3,5.9,2-15,5.9,2+3,5.20,8\)
\(=20,8.\left(-15,5+3,5\right)+9,2.\left(-15,5+3,5\right)\)
\(=\left(-15,5+3,5\right).\left(20,8+9,2\right)\)
\(=\left(-12\right).30=-360\)
b) \(\left[\left(-19,95\right)+\left(-45,75\right)\right]+\left[4,95+5,75\right]\)
\(=\left[\left(-19,95\right)+4,95\right]+\left[\left(-45,75\right)+5,75\right]\)
\(=-15+\left(-40\right)=-55\)
Bài 2 :
\(a,2.\left|2x-3\right|=1\)
\(\Leftrightarrow\left|2x-3\right|=\frac{1}{2}\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-3=\frac{1}{2}\\2x-3=-\frac{1}{2}\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}2x=\frac{1}{2}+3\\2x=-\frac{1}{2}+3\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}2x=\frac{7}{2}\\2x=\frac{5}{2}\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\frac{7}{4}\\x=\frac{5}{4}\end{matrix}\right.\)
Vậy : \(x\in\left\{\frac{7}{4},\frac{5}{4}\right\}\)
\(b,7.5-3\left|5-2x\right|=-4.5\)
\(\Leftrightarrow3.\left|5-2x\right|=7.5-\left(-4.5\right)=12\)
\(\Leftrightarrow\left|5-2x\right|=4\)
\(\Leftrightarrow\left[{}\begin{matrix}5-2x=4\\5-2x=-4\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}2x=1\\2x=9\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\frac{1}{2}\\x=\frac{9}{2}\end{matrix}\right.\)
Vậy : \(x\in\left\{\frac{1}{2},\frac{9}{2}\right\}\)
\(c,\left|3x-4\right|+\left|3y+5\right|=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}3x-4=0\\3y+5=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}3x=4\\3y=-5\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=\frac{4}{3}\\y=-\frac{5}{3}\end{matrix}\right.\)
Vậy : \(\left(x,y\right)=\left(\frac{4}{3},-\frac{5}{3}\right)\)
Bài 3 :
a) \(2^{300}\) và \(3^{200}\)
Ta có : \(2^{300}=\left(2^3\right)^{100}=8^{100}\)
\(3^{200}=\left(3^2\right)^{100}=9^{100}\)
mà : \(9^{100}>8^{100}\Rightarrow3^{200}>2^{300}\)
Vậy : \(3^{200}>2^{300}\)
b) \(2^{30}+3^{30}+4^{30}\) và \(3.2.4^{10}\)
Ta có : \(3.2.4^{10}=6.\left(2^2\right)^{10}=6.2^{20}=3.2^{21}\)
Ta thấy : \(2^{30}>3.2^{21}\Rightarrow2^{30}+3^{30}+4^{30}>3.2^{21}\)
hay : \(2^{30}+3^{30}+4^{30}>3.2.4^{10}\)
Vậy : \(2^{30}+3^{30}+4^{30}>3.2.4^{10}\)
Chúc bạn học tốt !
2. Tìm y
a) y : 15 - 34,87 = 52,21 + 6
b) 76,22 - y x 3 = 30,61 x 2
Tìm y:
76,22 - y x 3 = 61,22
76,22 - y x 3 = 61,22
y x 3 = 76,22 - 61,22
y x 3 = 15
y = 15 : 3
y = 5
76,22 - y x 3 = 61,22
<=>y x 3=76,22-61,22
<=>y x 3=15
<=>y=5
k mik nhé .Thanks
76,22 - y x 3 = 61,22
y x 3 = 76,22 - 61,22
y x 3 = 15
y = 15 : 3
y = 5
~Moon~