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A boy is five time as old as his sister. Two years ago the sum of the square of their ages was 170. Find the present age of his sister? |
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Answer» yeah Step-by-step EXPLANATION: let's sis=X-2 boy=5x-2 now, (x-2+5x-2)²=170 (6x-4)²=170 36x²-48x+16=170 36x²-48x+16-170=0 36x²-48x-154=0 (let's compare with ax²+bx+c) where a=36 b=-48 c=-154 then use FORMULA
x=±b√b²-4ac/2a (then find x value ) then AGE of sis will be x value .then find sis value ) |
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