Đáp án:
$1)
a)\dfrac{13}{8}\\
b)-14x+7\\
c)
x^2-12x+35\\
d)
2x-\dfrac{5}{4}$
Giải thích các bước giải:
$1)
a) \left | \dfrac{-3}{4} \right |+0,5.\left ( \dfrac{\sqrt{11}}{2} \right )^2-\dfrac{1}{2}\\
=\dfrac{3}{4}+\dfrac{1}{2}.\dfrac{11}{4}-\dfrac{1}{2}\\
=\dfrac{3}{4}+\dfrac{11}{8}-\dfrac{1}{2}\\
=\dfrac{6}{8}+\dfrac{11}{8}-\dfrac{4}{8}\\
=\dfrac{13}{8}\\
b) 3(2x-1)-5(4x-2)\\
=6x-3-20x+10\\
=-14x+7\\
c)
(x-7)(x-5)\\
=x^2-5x-7x+35\\
=x^2-12x+35\\
d)
\left ( x-\dfrac{1}{2} \right ).\left ( x+\dfrac{1}{2} \right )-(x-1)^2\\
=x^2-\left ( \dfrac{1}{2} \right )^2-(x^2-2x+1)\\
=x^2-\dfrac{1}{4}-x^2+2x-1\\
=2x-\dfrac{1}{4}-1\\
=2x-\dfrac{1}{4}-\dfrac{4}{4}\\
=2x-\dfrac{5}{4}$
