Giải các phương trình sau:
a, 3x – 2 = 2x – 3
b, 11x + 42 – 2x = 100 – 9x – 22
c, 10x + 3 – 5x = 4x + 12
d, 2x – (3 – 5x) = 4 (x + 3)
e, x (x + 2) = x (x + 3)
f, 2 (x – 3) + 5x (x – 1) = $5^{2}$
Giải các phương trình sau:
a, 3x – 2 = 2x – 3
b, 11x + 42 – 2x = 100 – 9x – 22
c, 10x + 3 – 5x = 4x + 12
d, 2x – (3 – 5x) = 4 (x + 3)
e, x (x + 2) = x (x + 3)
f, 2 (x – 3) + 5x (x – 1) = $5^{2}$
Đáp án:
Giải thích các bước giải:
`a,`
`3x-2=2x-3`
`=> 3x-2x=-3+2`
`=> x=-1`
`b,`
`11x+42-2x=100-9x-22`
`=> 11x-2x+9x=100-22-42`
`=> 18x=36`
`=> x= 2`
`c,`
`10x+3-5x=4x+12`
`=> 10x-5x-4x=12-3`
`=> x=9`
`d,`
`2x-(3-5x)=4(x+3)`
`=> 2x-3+5x=4x+12`
`=> 2x+5x-4x=12+3`
`=> 3x=15`
`=> x=5`
`e,`
`x(x+2)=x(x+3)`
`=> x(x+2)-x(x+3)=0`
`=> x(x+2-x-3)=0`
`=> -x=0`
`=> x=0`
`f,`
`2(x-3)+5x(x-1)=5^2`
`=> 2x-6+5x^2 – 5x=25`
`=> 5x^2 – 3x-31=0`
`=> (\sqrt5 x -(3\sqrt5)/(10) )^2 – 31,45 =0`
`=> (\sqrt5 x -(3\sqrt5)/(10) – \sqrt{31,45} )(\sqrt5 x -(3\sqrt5)/(10) + \sqrt{31,45} )=0`
`=> ` \(\left[ \begin{array}{l}\sqrt5 x -\frac{3\sqrt5}{10} – \sqrt{31,45}=0\\\sqrt5 x -\frac{3\sqrt5}{10} + \sqrt{31,45}=0\end{array} \right.\) `=>` \(\left[ \begin{array}{l}x=\frac{\frac{3\sqrt5}{10} + \sqrt{31,45}}{\sqrt5}\\x=\frac{\frac{3\sqrt5}{10} – \sqrt{31,45}}{\sqrt5}\end{array} \right.\)
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