Solve for k : ( k + 1) ( 8k - 1) = 45
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(k+1)(8k-1)=45
8k²-k+8k-1=45
8k²+7k=46
8k²+7k-46=0
a=8,b=7,c=-46
Roots are (-b+√b²-4ac)/2a,(-b-√b²-4ac)/2a
⇒(-7+√(7)²-4(8)(-46))/2(8),(-7-√(7)²-4(8)(-46))/2(8)
⇒(-7+√49+1472)/16,(-7-√49+1472)/16
⇒(-7+√1521)/16,(-7-√1521)/16
⇒(-7+39)/16,(-7-39)/16
⇒32/16,-46/16
⇒2,-2.87
∴The value of k is 2.
8k²-k+8k-1=45
8k²+7k=46
8k²+7k-46=0
a=8,b=7,c=-46
Roots are (-b+√b²-4ac)/2a,(-b-√b²-4ac)/2a
⇒(-7+√(7)²-4(8)(-46))/2(8),(-7-√(7)²-4(8)(-46))/2(8)
⇒(-7+√49+1472)/16,(-7-√49+1472)/16
⇒(-7+√1521)/16,(-7-√1521)/16
⇒(-7+39)/16,(-7-39)/16
⇒32/16,-46/16
⇒2,-2.87
∴The value of k is 2.
Answered by
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The value of k must be 2 or -2.87
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