Question 17
The real root of the equation $$2^{6x} + 2^{3x + 2} - 21 = 0$$ is
Solution
Let $$2^{3x}$$ = v
$$2^{6x} + 2^{3x + 2} - 21 = 0$$
= $$v^2+4v-21=0$$
=(v+7)(v-3)=0
v=3, -7
$$2^{3x}$$ = 3 or $$2^{3x}$$ = -7(This can be negated)
3x=$$\log_23$$
x=$$\log_23$$/3
Video Solution
CAT Quant Questions | CAT Quantitative Ability
CAT Averages, Ratio and Proportion QuestionsCAT Geometry QuestionsCAT Progressions and Series QuestionsCAT Inequalities QuestionsCAT Geometry Questions
CAT DILR Questions | LRDI Questions For CAT
CAT Special Charts QuestionsCAT Data Interpretation QuestionsCAT Table with Missing values QuestionsCAT Coins and Weights QuestionsCAT Routes And Networks Questions
