Question

1.преобразуй выражение
a) (7-y)²
b)(8-k)(8+k)

2.вычислить рациональным способом
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Answer 1

1.

(7-y)²=7²-2*7y+y²=49-14y+y²

(8-k)(8+k)=8²-k²=64-k²

2.

24²-28*24+14²=24²-2*14*24+14²=(24-14)²=10²=100

$\frac{36,5^{2}-3,5^{2}}{26,5^{2} -15,5^{2} } =\frac{(36,5-3,5)(36,5+3,5)}{(26,5-15,5)(26,5+15,5)} =\frac{33*40}{11*42} =\frac{3*40}{3*14} =\frac{20}{7} =2\frac{6}{7} \\ \\ 99^{2}=(100-1)(100-1)=100^{2}-2*100+1=10000-200+1=9801$

3.

(y+3)²-y(y+3)=12

y²+6y+9-y²-3y=12

3y=12-9

3y=3

y=1

4.

(y+5)(y-5)-(y+2)²<30

y²-25-y²-4y-4<30

-4y<30+25+4

-4y<59

4y > -59

y > -14,75

5.

7y²-28c²=7(y²-4c²)=7(y-2c)(y+2c)

(2y²)³+(3k)³=(2y²+3k)(4y⁴-6y²k+9k²)