Question

Tìm x biết:

1)25/12x+11/15=9/10

2)3/2x-2/5=1/3x-1/4

3)29/12[x]-5/6=3/8

4)[4x+3/4]-5/4=2

5)2^x+2^x+3=144

Answer 1

1) \(\frac{25}{12}.x+\frac{11}{15}=\frac{9}{10}\)

=> \(\frac{25}{12}.x=\frac{9}{10}-\frac{11}{15}\)

=> \(\frac{25}{12}.x=\frac{1}{6}\)

=> \(x=\frac{1}{6}:\frac{25}{12}\)

=> \(x=\frac{2}{25}\)

Vậy \(x=\frac{2}{25}\).

3) \(\frac{29}{12}.\left[x\right]-\frac{5}{6}=\frac{3}{8}\)

=> \(\frac{29}{12}.\left[x\right]=\frac{3}{8}+\frac{5}{6}\)

=> \(\frac{29}{12}.x=\frac{29}{24}\)

=> \(x=\frac{29}{24}:\frac{29}{12}\)

=> \(x=\frac{1}{2}\)

Vậy \(x=\frac{1}{2}\).

4) \(\left[4x+\frac{3}{4}\right]-\frac{5}{4}=2\)

=> \(\left[4x+\frac{3}{4}\right]=2+\frac{5}{4}\)

=> \(4x+\frac{3}{4}=\frac{13}{4}\)

=> \(4x=\frac{13}{4}-\frac{3}{4}\)

=> \(4x=\frac{5}{2}\)

=> \(x=\frac{5}{2}:4\)

=> \(x=\frac{5}{8}\)

Vậy \(x=\frac{5}{8}\).

5) 2^x + 2^x+3 = 144

⇔ 2^x + 2^x . 2³ = 144

⇔ 2^x . (1 + 2³) = 144

⇔ 2^x . 9 = 144

⇔ 2^x = 144 : 9

⇔ 2^x = 16

⇔ 2^x = 2⁴

=> x = 4

Vậy x = 4.

Chúc bạn học tốt!