ГДЗ до підручника «Алгебра» О.С. Істера. 7 клас

473. 1) -1 + 4х - 4х2 = -(1 - 4х + 4х2) = -(1 - 2х)2;

2) -40а + 25а2 + 16 = 25а2 - 40а + 16 = (5а - 4)2;

3) 24xy - 9x2 - 16y2 = -(9x2 - 24xy + 16y2) = -(3х - 4у)2;

4) -140x3y + 100x6 + 49y2 = 100x6 - 140x3y + 49y2 = (10x3 - 7y)2;

5) 4pq - 25р2 - 0,16q2 = -(25р2 - 4pq + 0,16q2) = -(5p - 0,4q)2;

6) -0,64m6 - 1,6m23n2 - n4 = -(0,64m6 + 1,6m3n2 + n4) = -(0,8m3 + n2)2.

474. 1) -9 - 30х - 25х2 = -(9 + 30х + 25х2) = -(3 + 5х)2;

2) -36b + 81b2 + 4 = 4 - 36b + 81b2 = (2 - 9b)2;

3) 42xy - 49х2 - 9y2 = -(49х2 - 42ху + 9y2) = -(7х - 3y)2;

4) -0,36а4 - 25b6 + 6а2b3 = -(0,36а4 - 6а2b3 + 25b6) = -(0,6а2 - 5b3)2.

479. 1) (х - 2)2 + 2(х - 2) + 1 = (х - 2 + 1)2 = (x - 1)2;

2) (a2 + 6a + 9) + 2(a + 3) + 1 = (a + 3)2 + 2(a + 3) + 1 = (a + 3 + 1)2 = (a + 4)2.

480. 1) x2 + 2 > 0; x2 > 0; 2 > 0;

2) x2 - 6x + 9 > 0; (x - 3)2 ≥ 0.