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

122. 1) 35 • 32 = 35+x; x = 2;

2) 27 • 28 = 21+x; x = 14;

3) 4x • 45 = 48; x = 3;

4) 98 : 9x = 95; x = 3.

123. 1) a2 • a5 = a7;

2) a8 • a1 = a9;

3) a4 • a8 • a7 = a19.

124. 1) b7 : b4 = b3;

2) b14 : b5 = b9;

3) b9 : b5 • b3 = b7;

4) b15 : b9 • b4 = b10.

125. 1) 1,89 : 1,8 = 1,89-x;

9 - 1 = 9 - x; x = 1;

2) 19x : 197 = 199; x = 16;

3) 412 : 4x = 47; x = 5.

126. 1) 87 = (23)7 = 221;

(162)5 = ((24)2)5 = 240;

2) 253 = (52)3 = 56;

6257 = (54)7 = 528.

127. 1) 97 = (32)7 = 314;

(812)5 = ((34)x)5 = 340;

2) 1004 = (102)4 = 108;

10009 = (103)9 = 1027.

129. 1) x5 • xn = x5+n;

2) x8 : xn = x8-n;

3) xn : (x8 • x9) = xn : x17 = xn-17;

4) x2n : xn • x3n+1 = x4n+1;

5) ((xn)3)5 = x15n;

6) (-x4)2n = x8n.