8a - 8b + 8c = 8( a - b + c )
8( a - b + c ) = 8( a - b + c )
a - b + c = a - b + c
0 = 0
(a-b)(a+b) = a² <span>- b</span>²<span>
1)
(x+1)(x-1)-(x+5)(x-5)+(x+1)(x-5) =
= (x</span>²-1) - (x² - 5²) + (x+1)(x-5) =
= x²-1-x²+25 + (x+1)(x-5) =
= 24 + x²+x-5x-5 =
<span>= x</span>² - 4x + 19<span>
2)
81a</span>⁸-(3a²-b³)(9a⁴+b⁶)(3a²+b³<span>) =
= </span>81a⁸-(3a²-b³)(3a²+b³) (9a⁴+b⁶) =
= 81a⁸- ((3a²)²-(b³)²) (9a⁴+b⁶) =
= 81a⁸- (9a⁴-b⁶) (9a⁴+b⁶) =
= 81a⁸- ((9a⁴)² - (b⁶)²) =
= 81a⁸- 81a⁸ - b¹² = b¹²
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
X^-n=1/x^n
27^(1/3)=3
log1/27 (7-4x)=log1/27 (3)
7-4x=3
4x=7-3=4
x=1