(8a-3a² +1)-(a-3a²)
8a-3a²+1-a+3a²
7а+1
2ab(a+b)-ab(a-b)
ab*(2a+2b-a+b)
ab*(a+3b)
<span>(x+2)(4x-5)=-3
4x</span><span>²-5x+8x-10+3=0
</span>4x²+3x-7=0
D=3²-4*(-7)*4=9+112=121
x(1) = -3+<span>√121/2*4 = -3+11/8 = 8/8 = 1</span>
x(2) = -3-√121/2*4 = -3-11/8 = - 14/8 = -7/4
Ответ: - 7/4; 1.
<span>
3/4x</span>²-2/5x=4/5x²+3/4 x<span>≠0
</span>3/4x²-2/5x-4/5x²-3/4=0
(15-8x-16-15x²)/20x²=0
(-1-8x-15x²)/20x²=0
-1-8x-15x²=0 |*(-1)
1+8x+15x²=0
D=8²-4*15=64-60=4
x(1) = -8+√4/15*2 = -8+2/30 = -6/30 = -1/5
x(2) = -8-√4/15*2 = -8-2/30 = -10/30 = -1/3
Ответ: - 1/5; -1/3.
Решение смотри в приложении
1)
x²y+x+xy²+y+2xy+2 = (x²y+xy²+2xy)+(х+у+2) =
= ху(х+у+2)
+(х+у+2) = (х+у+2)·(ху+1)
2)
9a²-16 = (3а)² - 4² = (3а- 4)·(3а+4)
3)
x²-8ax+16a² = x²- 2 ·х · 4а + (4a)² = (х - 4а)² = (х - 4а)·(х - 4а)
4)
(a+2b)²-(3a-b)² = ((a+2b)-(3a-b)) · ((a+2b) + (3a-b)) =
= (a+2b-3a+b) · (a+2b + 3a-b) = (- 2a +3b)·(4a+b)
5)
x²+2xy+y²-a² = (x²+2xy+y²) - a² = (x+y)² - a² = (x+y-a)·(x+y+a)