Question

Поможіть кроме 11 я дам 10 б

Answer 1

7.

(х-2у)²-(х+2у)(2у-х)=х²-4ху+4у²+ (х+2у)(х-2у)=х²-4ху+4у²+х²-4у²=2х²- 4ху

8.

(2+х)²-(х-2)²=16

4+4х+х²-(х²-4х+4)=16

4+4х+х²-х²+4х-4=16

8х=16

х=2

9.

(2а-1)(2а+1)(4а²+1)-16а⁴=(4а²-1)(4а²+1)-16а⁴=16а⁴- 1 - 16а⁴= - 1

10.

(2-3х)²=9

4-12х+9х²-9=0

9х²-12х-5=0

D= b²- 4ac=(-12)²- 4×9×(-5)=144+180=324

$x1 = \frac{ - b - \sqrt{d} }{2a} = \frac{12 - \sqrt{324} }{2 \times 9} = \frac{12 - 18}{18} = \frac{ - 6}{18} = - \frac{1}{3} \\ x2 = \frac{ - b + \sqrt{d} }{2a} = \frac{12 + \sqrt{324} }{2 \times 9} = \frac{12 + 18}{18} = \frac{30}{18} = \frac{10}{6} = 1 \frac{4}{6} = 1 \frac{2}{3}$