a, \(2x+3=15\Leftrightarrow x=6\)
b, \(2\left(42-x\right)=23\Leftrightarrow84-2x=23\Leftrightarrow x=\frac{61}{2}\)
c, \(2,5x+2,3x=144\Leftrightarrow x\left(2,5+2,3\right)=144\Leftrightarrow x=30\)
a,2 x X+3=15 b,
2 x X =15-3
2 x X=12
X=12 : 2
X=6
2×x+3=15
2×x=15-3
2×x=12
x=12:2
x=6
vậy x=6
2×(42-x)=23
(42-x)=23×2
(42-x)=46
x=42-46
x=-4
vậy x=-4
2,5×x+2,3×x=144
x×(2,5+2,3)=144
x×4,8=144
x=144:4,8
x=30
vậy x=30
a,\(2.x+3=15\)
\(< =>2x=15-3=12\)
\(< =>x=\frac{12}{2}=\frac{6}{1}=6\)
b, \(2.\left(42-x\right)=23\)
\(< =>84-2x=23\)
\(< =>2x=84-23=61\)
\(< =>x=\frac{61}{2}=30\frac{1}{2}\)
c, \(2,5.x+2,3.x=144\)
\(< =>x\left(2,5+2,3\right)=x.4,8=144\)
\(< =>x=\frac{144}{4,8}=30\)
Bài giải
\(a,\text{ }2x+3=15\)
\(2x=12\)
\(x=6\)
\(b\text{, }2\left(42-x\right)=23\)
\(84-2x=23\)
\(2x=84-23\)
\(2x=61\)
\(x=\frac{61}{2}\)
\(\text{c, }2,5\text{ x }x+2,3\text{ x }x=144\)
\(x\text{ x }\left(2,5+2,3\right)=144\)
\(4,8x=144\)
\(x=30\)