Думаю, как-то так:
(2-√3)²- √2(√6-1) +3√12= 2²-2*2*√3-(√3)² -√2*√6+√2 + 3√12=
= 4- 4√3- 3 - √12+ √2+ 3√12= 1 - 4√3 - 2√3 +√2 + 6√3 = 1 +√2
![\frac{ x^{2} -3}{2 \sqrt{3}- 2x } = \frac{(x- \sqrt{3})(x+ \sqrt{3} ) }{2*( \sqrt{3}-x) } = \frac{(x- \sqrt{3})(x+ \sqrt{3} )}{-2(x- \sqrt{3})} =- \frac{x+ \sqrt{3} }{2}](https://tex.z-dn.net/?f=+%5Cfrac%7B+x%5E%7B2%7D+-3%7D%7B2++%5Csqrt%7B3%7D-+2x+%7D+%3D++%5Cfrac%7B%28x-+%5Csqrt%7B3%7D%29%28x%2B+%5Csqrt%7B3%7D+%29+%7D%7B2%2A%28+%5Csqrt%7B3%7D-x%29+%7D+%3D+%5Cfrac%7B%28x-+%5Csqrt%7B3%7D%29%28x%2B+%5Csqrt%7B3%7D+%29%7D%7B-2%28x-+%5Csqrt%7B3%7D%29%7D+%3D-+%5Cfrac%7Bx%2B+%5Csqrt%7B3%7D+%7D%7B2%7D+)
![\frac{y+x-2 \sqrt{x*y} }{5 \sqrt{x} -5 \sqrt{y} } = \frac{( \sqrt{y}- \sqrt{x} )^{2} }{5( \sqrt{x} - \sqrt{y}) } = \frac{( \sqrt{y} - \sqrt{x}) ^{2} }{-5( \sqrt{y}- \sqrt{x} ) } =- \frac{ \sqrt{y}- \sqrt{x} }{5}](https://tex.z-dn.net/?f=+%5Cfrac%7By%2Bx-2+%5Csqrt%7Bx%2Ay%7D+%7D%7B5+%5Csqrt%7Bx%7D+-5+%5Csqrt%7By%7D+%7D+%3D+%5Cfrac%7B%28+%5Csqrt%7By%7D-+%5Csqrt%7Bx%7D+%29%5E%7B2%7D++%7D%7B5%28+%5Csqrt%7Bx%7D+-+%5Csqrt%7By%7D%29+%7D+%3D++%5Cfrac%7B%28+%5Csqrt%7By%7D+-+%5Csqrt%7Bx%7D%29+%5E%7B2%7D++%7D%7B-5%28+%5Csqrt%7By%7D-+%5Csqrt%7Bx%7D+%29+%7D+%3D-+%5Cfrac%7B+%5Csqrt%7By%7D-+%5Csqrt%7Bx%7D++%7D%7B5%7D+)
X=2y-3
3(2y-3)+y=1
6y-9+y=1
x=2y-3
7y=10
x=2y-3
y=10/7
x=2*10/7-3
x=20/7-3=2 6/7-3=-1/7
y=1 3/7
0,5а⁶-12,5 = 0,5а⁶-12,5=0,5(а²)³<span>-12,5 при </span>а²=5
0,5·5³-12,5=0,5·125-12,5=62,5-12,5=50
<u>Ответ: 50</u>