lf half of a number is equal to 0.07 times of another number, then their ratio will be
50 : 7
5 : 7
7 : 50
1 : 14
If a + b + c = 0, then a4 + b4 + c4a2b2 + b2c2 + c2a2 = ?
4
2
1
16
B.
a + b + c = 0⇒ a + b2 = - c2⇒ a2 + b2 + 2ab = c2 ⇒ a2 + b2 - c2 = - 2ab⇒ a2 + b2 - c2 = - 2ab2⇒ a4 + b4 + c4 + 2a2b2 - 2b2c2 - 2c2a2 = 4a2b2∴ a4 + b4 + c4 = 2a2b2 + 2b2c2 + 2c2a2∴ a4 + b4 + c4a2b2 + b2c2 + c2a2 = 2a2b2 + b2c2 + c2a2a2b2 + b2c2 + c2a2 = 2
If a : b = 4 : 5, b : c = 6 : 9, c : d = 15 : 19, then a : b : c : d is
8 : 10 : 15 : 19
10 : 11 : 15 : 19
8 : 9 : 15 : 19
19 : 15 : 6 : 8