Question

Solve the following questions;
(a)If the first and last terms of an A.P are 10 and 15 respectively.What will be the number of terms in it,if their sum is 125?
(b) Write log 64/729 in its expansion form?
(c)solve 8x-2y=28 and x+4y=-5
(d)for what value of k(-4) is a zero of the polynomial x^2-x-(2k+2)?
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Answer 1

Answer:

a) 10

b)log3power6 to base 2power3

c)-3

d)k=9

Step-by-step explanation:

a) sn=n/2(a+l)

125×2=n(10+15),

250=n(25)

250/25=n

10=n

number of terms is equal to 10

c) 8x-2y=28

x+4y=-5

multiple by 8 in eq 2

8x-2y=28

8x+32y=-40

subtract each other ration

-34y=68

y=-1/2

x=-3

d) Here given that -4 is a zero of the polynomial it means that -4 is a solution of this equation so find the value of k by putting -4 on the place of x and also remember one thing at the time of solving these type of questions that is sign because it goes reversed after changing the side it may be from left to right or vice versa

solution:

x^2-x-(2k+2)=0

(-4^2)-(-4)-2k -2=0

16+4-2k-2=0

2k=18

k=9