SAT Math · Nonlinear equations in one variable · medium
The equation 2^x = x + 5 can be solved by finding the x-coordinates where the graphs of y=2^x and y=x+5 intersect. How many real solutions…
The equation can be solved by finding the -coordinates where the graphs of and intersect. How many real solutions does this equation have?
Answer and explanation
Answer: A: 2
Compare the graphs of and . At , both equal 8, so one intersection is . For large , the exponential grows faster than the line, so there are no more intersections to the right. For negative , the line decreases through zero at , while stays positive and small; at the exponential is above the line (), but at the line is above (). So they cross once between and . That is 2 solutions, choice A.
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