please help me with explanation
Answers
13. ABCD is a quadrilateral , thus sum of all interior angles will be 360° .
angle A + B + C + D = 360°
60° + 70° + 80° + D = 360°
D = 360-60-70-80
D = 150°
thus x = 150°
9. Six rational numbers between 1 and 2
1/1 × 8/8 = 8/8
2/1 × 8/8 = 16/8
rational numbers between 8/8 and 16/8 are : 9/18, 10/18, 11/18, 12/18, 13/18, 14/18, 15/18
these are only the rational numbers between 1 and 2
14. let sneha's father's age be x .
then her grandfather's age becomes x+26
and sneha's age becomes x-29
sum of their ages = 135
x + x+26 + x-29 = 135
3x = 135 + 29 - 26
3x = 138
x = 138/3
x = 46
so, sneha's father's age is 46
sneha's grandfather's age is 46+26 = 72
sneha's age is 46-29 = 17
Verification : 46+72+17 = 135
19. line measuring 35 cm is equal to line measuring 23cm + x
so, 35 = 23 + x
35-23 = x
12 cm = x
7. No, 9 , 10 and 11 are not pythagorean triplets
since , 9^2 + 10^2 ≠ 11
81 + 100 ≠ 121
181 ≠121
thus, 9, 10 and 11 aren't pythagorean triplets
8. (6a - 1) ( 3a^2 + 3a - 10)
= 6a ( 3a^2 + 3a - 10) - 1 ( 3a^2 + 3a - 10)
= 18a^3 + 18a^2 - 60a -3a^2 - 3a + 10
= 18a^3 + 18a^2 - 3a^2 - 60a -3a + 10
= 18a^3 + 15a^2 - 63a + 10
sorry for all r not attempted ...coz I'm a bit busy
but hope this helps u...