Question

Спростіть вираз 3х(4х-1)-7х-6(2x²-3х) та знайдіть його значення, якщо х=-3/4

Answer 1

$3x \times (4x - 1) - 7x - 6 (2 {x}^{2} - 3x) = 3 \times ( - \frac{3}{4} ) \times (4 \times ( - \frac{3}{4} ) - 1) - 7 \times ( - \frac{3}{4} ) - 6(2 \times ( - \frac{3}{4} {)}^{2} - 3 \times ( - \frac{3}{4} )) = 3 \times ( - \frac{3}{4} ) \times ( - 3 - 1) + \frac{21}{4} - 6(2 \times ( \frac{3}{4} {)}^{2} + \frac{4}{9} ) = 3 \times ( - \frac{3}{4} ) \times ( - 4) + \frac{21}{4} - 6(2 \times \frac{9}{16} + \frac{9}{4} ) = 3 \times 3 + \frac{21}{4} - 6( \frac{9}{8} + \frac{9}{4} ) = 9 + \frac{21}{4} - 6 \times \frac{27}{8} = 9 + \frac{21}{4} - 3 \times \frac{27}{4} = 9 + \frac{21}{4 } - \frac{81}{4} = - 6$