Question

1.) Find the sum of 2+4+6+... to 21 terms?
2.) Solve for x: 2x²-7x+3=0
3.) Find the values of k for which the following system of linear equation has infinitely many solutions:
x+(k+1)y=5, (k+1)x+9y=(8k-1)
4.) ∆ABC is an obtuse triangle, obtuse angled at B. If AD is perpendicular to CB meeting CB produced in D. Prove that AC²=AB²+BC²+BC.BD.

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Answer 1

Answer:

Step-by-step explanation:

1)Sn=21/2(4+40)

=21/2(44)

=21x22

=462

2)2x^2-7x+3

=2x^2-6x-x+3

=(x-1)(2x-1)

= x=1 and x=1/2

3) 1/k+1=k+1/9

= k+1=3 and k+1=-3

=k=2 and k=-4

4)see the attachment