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If `(x)/((x+2)(x+3))=(A)/(x+3)+(B)/(x+2)`, then `A-B` is `=`_________.A. `4`B. `5`C. `-6`D. `2` |
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Answer» Let `(x)/((x+2)(x+3))=(A)/(x+3)+(B)/(x+2)` `(x)/((x+2)(x+3))=(A(x+2)+B(x+3))/((x+2)(x+3))`. Consider `A(x+2)+B(x+3)=x` Put `x=-3`, `-A=-3impliesA=3` Put `x=-2`, `B=-2` `:. A-B=3-(-2)=3+2=5`. |
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