Verified answer

Объяснение:

1.

6х+5=5х-7(х-3)

6х+5=5х-7х+21

6х+5= -2х+21

6х+2х=21-5

8х=16

х=16:8

х=2

2.

1) с¹⁸:с¹⁵•с²=с³•с²=с⁵

2) (а²)⁵:а=а¹⁰:а=а⁹

3) (с⁵)³•с⁴=с¹⁵•с⁴=с¹⁹

3.

1) 2а³•(-0,5а)= -а⁴

2) -3а³•(-аb²)⁴= -3a³•a⁴b⁸= -3a⁷b⁸

4.

1)

(3x²-6x-5)(2x²-3x-4)=

=6х⁴-9х³-12х²-12х³+18х²+24х-10х²+15х+20=

=6х⁴-21х³-4х²+39х+20

2)

5х(х³-4х+6)=5х⁴-20х²+30х

3)

(х-2)(2х+3)=2х²+3х-4х-6=2х²-х-6

5.

1) 5а²-20аb=5a(a-4b)

2) 7x³-14x⁵=7x³(1-2x²)

3) 3a-3b+a=4a-3b

6.

1)

(2х-3)²-(2х-5)(2х+5)+12х=34

(2х-3)²-(2х-5)(2х+5)+12х=

=4х²-12х+9-(4х²-25)+12х=

=4х²-12х+9-4х²+25+12х=34

34=34 - верно.

2)

(3х-2)(3х+2)-(3х-4)²-24х= -20

9х²-4-(9х²-24х+16)-24х=

=9х²-4-9х²+24х-16-24х= -20

-20= -20 - верно