Question

С
13.15. Решите уравнение:
1) (x +10)(х - 9) - (х - 8) = 0;
2) (х + 11)(х + 9) - (х-3)(х + 40) = 0;
3) (x - 6)(7 + х) + (3 - x)(3 + х) = 0;
4) (x-4)(4 + х) - (1 - x)(9 - x) = 0.​

Answer 1

Объяснение:

1) (x+10)(x-9)-(x-8)=0

x²+x-90-x+8=0

x²-82=0

x²=82

x=±√82

2) (x+11)(x+9)-(x-3)(x+40)=0

x²+20x+99-(x²+37x-120)=0

x²+20x+99-x²-37x+120=0

20x-37x+99+120=0

219-17x=0

17x=219

$x = 12 \frac{15}{17}$

3) (x-6)(7+x)+(3-x)(3+x)=0

7x+x²-42-6x+9-x²=0

x-33=0

x=33

4) (x-4)(4+x)-(1-x)(9-x)=0

4x+x²-16-4x-(9-x-9x+x²)=0

x²-16-9+10x-x²=0

10x=25

x=25/10

x=2,5