Поможете контрольная завтра плиииз

1.
A)
$(b - 4) {}^{2} = \\ {b}^{2} - 2b \times 4 + {4}^{2} = {b}^{2} - 8b + 16$
Б)
$(a + 5x) {}^{2} = \\ {a}^{2} + 2a \times 5x + (5x) {}^{2} = \\ {a}^{2} + 10ax + 25 {x}^{2}$
В)
$(1 - 8k)(1 + 8k) \\ {1}^{2} - (8k) { }^{2} = 1 - 64 {k}^{2}$
Г)
$(4b + 5c)(4b - 5c) = \\ (4b) {}^{2} - (5c) {}^{2} = 16 {b}^{2} - 25 {c}^{2}$
2.
А)
${y}^{2} - 36 = (y - 6)(y + 6)$
Б)
${n}^{2} - 10n + 25 = (n - 5) {}^{2}$
В)
$16m {}^{6} n {}^{2} - 81 {x}^{2} = \\ (4m {}^{3}n - 9x)(4m {}^{3} n + 9x)$
Г)
$(x + 2) {}^{2} - (x - 2) {}^{2} = \\ {x}^{2} + 4x + 4 - {x}^{2} + 4x - 4 = 8x$

3.
$(y + 4) {}^{2} - 5y(y - 6) \\ {y}^{2} + 8y + 16 - 5 {y}^{2} + 30y \\ - 4 {y}^{2} + 38y + 16$

4.
А)
$x( x - 4) + (3 - x)(3 + x) = - 6 \\ {x}^{2} - 4x + 9 - {x}^{2} = - 6 \\ - 4x + 9 = - 6 \\ - 4x = - 6 - 9 \\ - 4x = - 15 \\ x = \frac{15}{4} = 3 \frac{3}{4} = 3.75$
Б)
$(5 {x}^{4} - 7 {y}^{2} )(5 {x}^{4} + 7 {y}^{2} ) \\ (5 {x}^{4) {}^{2} } - (7 {y}^{2} ) {}^{2} \\ 25 {x}^{8} - 49 {y}^{4}$

5. Извини, но никак не получается его решить.