Let {{MATH_4}}. Use the limit definition of the derivative above to find {{MATH_5}}. {{CMD_6}} Write {{MATH_7}} {{CMD_8}} Now substitute {{MATH_9}} to obtain {{MATH_10}} {{CMD_11}} To analytically compute this limit, we should multiply {{MATH_12}} by the fraction: {{MATH_13}} {{CMD_14}} Now we have {{MATH_15}} so we may cancel a factor of {{MATH_16}}, {{MATH_17}} and finally see that: {{MATH_18}} {{CMD_19}} {{CMD_20}} {{CMD_21}} {{CMD_22}} {{CMD_23}} {{CMD_24}}