Question

Решите пожалуйста уравнения:
1) (4х-3у)(3х+у)-(1,5х-5у)(8х-4у);
2) (х+5)(х-3)-(х+1)(х-4)=4х.

Answer 1

1.

(4x-3y)(3x+y) – (1,5x)(8x-4y)=

=12x²+4xy-9xy-3y²-(12x²-6xy-40xy+20y²)=

=12x²-5xy-3y²-12x²+6xy+40xy-20y²=

=41xy-23y²

2.

(x+5)(x-3) – (x+1)(x-4)=4x

X²-3x+5x-15-(x²-4x+x-4)=4x

X²+2x-15-x²+4x-x+4=4x

5x-11-4x=0

X=11

Поверка:

(11+5)(11-3) – (11+1)(11-4)=4*11

16*8-12*7=44

128-84=40

       40=40