Tìm x biet.

A) (1 và 1/3 × x + 0,5) ×1 và 1/6 = 5,25

B)x ×120% = 2 và 1/4 - 15

C) (4,5- 2x)× 3 và 2/3=11/15

D) 3/4 × x -2/3 × x = 2/7 × 1/6 × 5/7 × 1/6

Giúp mik vs

Đáp án:

  A) \( (1 + \frac{1}{3}x + 0,5) \times (1 + \frac{1}{6}) = 5,25 \) \( (1 + \frac{1}{3}x + 0,5) \times (1 + \frac{1}{6}) \) \[ (1 + \frac{1}{3}x + 0,5) \times (1 + \frac{1}{6}) = (1,5 + \frac{1}{3}x) \times (1,1667) \] \[ = 1,75 + \frac{1}{3}x \times 1,1667 \] \[ = 1,75 + 0,1944x \] \[ 1,75 + 0,1944x = 5,25 \] \[ 0,1944x = 5,25 - 1,75 \] \[ 0,1944x = 3,5 \] \[ x = \frac{3,5}{0,1944} \] \[ x ≈ 18 \] B) \( x \times 120\% = 2 + \frac{1}{4} - 15 \) \( 2 + \frac{1}{4} - 15 \): \[ 2 + \frac{1}{4} - 15 = - 13,75 \] \[ x \times 1,20 = -13,75 \] \[ x = \frac{-13,75}{1,20} \] \[ x ≈ -11,46 \] C) \( (4,5 - 2x) \times 3 \frac{2}{3} = \frac{11}{15} \) \( (4,5 - 2x) \times 3 \frac{2}{3} \): \[ (4,5 - 2x) \times 3 \frac{2}{3} = (4,5 - 2x) \times \frac{11}{3} \] \[ = 4,5 - 2x \times \frac{11}{3} \] \[ = 4,5 - \frac{22}{3}x \] \[ 4,5 - \frac{22}{3}x = \frac{11}{15} \] \[ - \frac{22}{3}x = \frac{11}{15} - 4,5 \] \[ - \frac{22}{3}x = -4,3667 \] \[ x = \frac{-4,3667}{-\frac{22}{3}} \] \[ x ≈ 0,675 \] D) \( \frac{3}{4}x - \frac{2}{3}x = \frac{2}{7} \times \frac{1}{6} \times \frac{5}{7} \times \frac{1}{6} \) \[ \frac{2}{7} \times \frac{1}{6} \times \frac{5}{7} \times \frac{1}{6} = \frac{5}{756} \] \[ \frac{3}{4}x - \frac{2}{3}x = \frac{5}{756} \] \[ \frac{9}{12}x - \frac{8}{12}x = \frac{5}{756} \] \[ \frac{1}{12}x = \frac{5}{756} \] \[ x = \frac{\frac{5}{756}}{\frac{1}{12}} \] \[ x = \frac{5}{756} \times 12 \] \[ x = \frac{5 \times 12}{756} \] \[ x = \frac{60}{756} \] \[ x = \frac{5}{63} \] Vậy các giá trị của \( x \) là: A) \( x ≈ 18 \); B) \( x ≈ -11,46 \) ;C) \( x ≈ 0,675 \) ;D) \( x = \frac{5}{63} \)